Structures That Recur

System archetypesPart V · Pattern and Judgment · Chapter 10 of 12 · the first of two chapters on system archetypes

Which stories play out again and again? A few loop structures recur in situations that share nothing else: a fix that brings its problem back, growth that meets a limit, a shared resource used up. A system archetype is a causal loop diagram with the name of its structure written on it, and matching reads whether its loops have that structure.

Print this chapter, with a sheet for each exercise and the answers at the back, from its PDF.

Signals you need this diagram

A fix worked at first, and the problem came back worse.
Growth slowed while the effort behind it kept rising.
A fast remedy goes on being used, and a slower one is never started.
Of two people or groups drawing on one resource, the one ahead pulls further ahead.
Several users of one shared resource each take more, and each gets less.
A situation’s loops sound like a story from somewhere else.

Spraying a valley’s rice

Farmers in a river valley spray their rice when pests build up, and within days the pests fall. The spray also kills the spiders and parasitic wasps that prey on the pests. With fewer of them, the pests come back in greater numbers over the following seasons, and the farmers spray more often. In Asia’s rice fields, the International Rice Research Institute reports that early sprays kill the brown planthopper’s natural enemies and make its outbreaks ten times more likely.

B1, fewer pests, is the spray’s relief; R1, pests return, runs through the predators it kills. The loops match the archetype written on the diagram, fixes that fail, with its delay.

What the notation expresses

A system archetype is drawn with a causal loop diagram’s marks: variables, effects with their polarities, loops and delays. It adds two kinds of words: a variable’s role, in small type above its name, and a declared archetype, one line beginning Archetype:.

Archetypes

An archetype is a named loop structure that recurs across situations. Kim opens fixes that fail with a squeaky wheel: water stops the squeak, the wheel rusts, and it squeaks louder. The rice valley has the same loops. Each archetype is written as a template: its variables, its effects with their polarities, its loops with their kinds, and where a delay belongs.

A declared archetype is a line of words on the diagram, Archetype: fixes that fail: a hypothesis that the diagram’s loops hold that archetype. A diagram may carry several.

Matching

A match is a place in a diagram where an archetype’s loops sit: each of the template’s variables stood in by a different variable of the diagram, each template effect drawn as one effect or a chain of up to four, and every loop of the template of the same kind, by the parity rule. A chain holds variables the template leaves out: pests → spraying could run through damaged leaves.

Matching reads loops, their kinds and where delays sit, never what a variable is: whether natural predators are spiders or rainfall, or whether spraying relieves anything. So a match is a hypothesis about structure, never a verdict on the situation. A near miss is an archetype’s loops found with one of them of the other kind, or a match without a delay the archetype has.

In the lab, the matches are listed after every change, and each declared archetype is checked against them. Finding archetypes by algorithm has a precedent in simulation models (Schoenenberger, Schmid and Schwaninger, 2015).

Symptomatic and fundamental solutions

A symptomatic solution relieves a symptom quickly: spraying, with symptomatic solution written above its name. A fundamental solution acts on the cause, more slowly, and is written fundamental solution. The rice valley has none drawn. One drawn in reply to the pests, lowering them after a delay and weakened as the predators fall, would make it a shifting the burden.

Which remedy is which depends on who is asked: Kim writes that there may be no agreement on whether a remedy is symptomatic or fundamental. A role is written by whoever draws the diagram, and checked only for fitting a match: its variable must stand where the archetype puts that role.

Check your understandingRain comes through a cracked roof tile into an attic. Whenever it rains, someone sets out pans and empties them, and the attic floor stays dry. Replacing the tile would take a roofer and a dry week, and the longer the pans keep the floor dry, the less anyone thinks of calling one. In a system archetype of the attic, which variable is the symptomatic solution?

water on the attic floor

Not quite. That is the problem symptom: the quantity the pans and the new tile both lower.

pans emptied

Yes. The pans lower the water on the floor within the hour and leave the crack as it was, so they relieve the symptom quickly: the symptomatic solution.

tiles replaced

Not quite. Replacing the tile acts on the cause, more slowly, after a roofer and a dry week: the fundamental solution, with the delay on its effect.

how used to the leak the household is

Not quite. That is the side effect: the pans raise it, and it lowers the tiles replaced, closing a reinforcing loop through both remedies, as shifting the burden has it.

Side effects

A side effect is a consequence of the symptomatic solution, usually delayed: natural predators, which spraying lowers, with side effect written above the name. In fixes that fail it worsens the problem symptom; in shifting the burden it weakens the fundamental solution. The role goes on the consequence, not on the symptom it brings back.

Fixes that fail

The fix loop (B1) relieves the problem symptom; the side effect’s loop (R1) brings it back, after a delay on one of the effects through the side effect. Which of the two drives behavior when is loop dominance: the fix first, the side effect after its delay.

The answers to chapter 4’s CL 05, borrowing to get to the end of the month, and chapter 5’s CL 07, antibiotics, match fixes that fail with its delay.

Limits to growth

A reinforcing loop, the growth loop, and a balancing loop, the limit loop, share performance: efforts raise performance and performance spurs efforts, until the limiting action holds performance back. Kim calls limits to growth limits to success, and puts the leverage in removing what limits growth, not in pushing harder on the growth loop: a leverage point on the limiting action. What sets the limit, the constraint, acts from outside both loops, so the template leaves it out.

The answer to chapter 5’s CL 09, an old town and its visitors, matches no limits to growth: its two loops share an effect, holiday lets → visitors, where limits to growth’s share one variable.

Shifting the burden

Two balancing loops relieve one problem symptom: the symptomatic solution’s at once, the fundamental solution’s after a delay. The symptomatic solution’s side effect weakens the fundamental solution, closing a reinforcing loop through both. Its symptomatic loop and reinforcing loop together match fixes that fail, the side effect’s way back to the problem symptom running through the fundamental solution. Where that way is a chain of four effects or fewer, as in the figure, every shifting the burden holds one.

The answer to chapter 5’s CL 08, a parent who finishes the homework, matches shifting the burden with its delay.

Success to the successful

Two reinforcing loops share one allocation between A and B: success of A wins A a larger share, and a larger share to A is less to B, whose success falls and wins it less again. Which side ends ahead depends on where each started, as much as on what each could do with an equal share (Kim).

Any two reinforcing loops sharing one variable match it, whatever their polarities: success of B named as failure of B turns its two − into +.

Tragedy of the commons

Each user’s activity raises their net gains, which raise their activity (R1, R2). All activity adds to total activity, which, after a delay, lowers the gain per activity of every user (B1, B2). A lower gain per activity raises each user’s activity, closing two more reinforcing loops through total activity (R3, R4), which Kim draws and leaves unnamed. The resource limit sits outside the loops. Where the shared resource accumulates, as the fish on AR 05’s fishing ground do, it is a stock. Three users give three matches, one for each pair. Kim puts the remedy above the level of any one user.

A variable named as its opposite

In the rice valley, natural predators fall as spraying rises, and their fall raises the pests: two − effects where the template’s side effect has two +. Named predators lost, the same variable would carry two +.

A variable named as its opposite changes the polarity of every effect into and out of it. A loop through it passes two of those, so the parity rule gives it the same kind, and the match holds, with the variable reported as named as its opposite.

Check your understandingA gym fills up every January: each new member brings friends along, and the friends join. By February the crowded floor puts members off. Someone draws it with space on the gym floor where crowding would go: members → space on the gym floor −, space on the gym floor → members +, beside members → friends brought along → members, both +. Does it match limits to growth?

Yes, with space on the gym floor named as its opposite

Yes. Members and friends brought along close a reinforcing loop. Members and space on the gym floor close a loop with one −, so it is balancing. The limiting action rises with performance; space falls as members rise, so it stands as the limiting action named as its opposite.

No: the archetype has performance → limiting action +, and this effect is −

Not quite. Matching reads loop kinds, not each effect's polarity. Naming crowding as space on the gym floor changes the polarity of both effects on the loop through it, so the loop keeps one − and stays balancing.

No: with space where crowding would go, the loop through it is reinforcing

Not quite. Count the − effects: members → space on the gym floor is the only one. One is odd, so the loop is balancing, as limits to growth has it.

What stays informal

What a variable is: matching reads structure, so whether the valley’s story is a fix that fails, whether these predators eat these pests, is a question for evidence about the valley.

Timing beyond where delays sit: a delay shows that a change arrives late, not whether a season or a decade late. That goes in a behavior note or a sentence.

Leverage beyond the leverage point’s box: the box marks a hypothesis about where to act; why there, and how hard to push, go in prose beside the diagram.

The bad diagram

What’s wrong with this diagram of the rice valley?

Its variables, polarities, loops and declaration are the corrected diagram’s, and its loops match fixes that fail. But natural predators → pests carries no delay, as if the pests came back the day the spray killed their predators. The lab’s check reports:

Matches fixes that fail without its delay: the side effect comes late, and no effect on spraying → natural predators → pests has a delay. Brief: fixes that fail, with its delay.

The corrected diagram

Corrected, natural predators → pests carries a delay: the pests come back over seasons, after weeks of relief.

Bad diagram

Corrected diagram

Labels unchanged. Effects: 1 delay added. Now matched with its delay: fixes that fail.

Notation moves

Notation move	When	What it shows	Example
Declare an archetype	The loops have a structure that recurs across situations	A hypothesis about the loops, checked against the matches	Archetype: fixes that fail

Write symptomatic solution above a variable	It relieves a symptom quickly	The fast remedy	spraying

Write fundamental solution above a variable	It acts on the cause, more slowly	The slow remedy the side effect weakens	tiles replaced, under a leaking roof

Write side effect above a variable	A consequence of the symptomatic solution comes back	Where the later loop leaves the fix	natural predators

Mark the archetype’s delay		Which change comes late	natural predators → pests

Name a variable as its opposite	Its name reads better the other way round	The same match	natural predators for predators lost

Propose a leverage point on the limiting action	Growth meets a limit	Where Kim puts the leverage	crowding, in a gym that fills every January

Check your understanding

Check your understandingEvening pick-up games on a park's basketball court: players bring friends, and the friends come back the next week. As the court fills, players wait longer between games, and some stop coming. A diagram of the court, with players, friends brought along and waiting time, matches limits to growth. What does the match show?

That the diagram's loops have the structure of limits to growth

Yes. Matching reads loops, their kinds and where delays sit: here a reinforcing loop and a balancing loop sharing players. Whether waiting time is what keeps players away is a question about the court, not about the drawing.

That players stop coming because of the waiting

Not quite. That is the story the diagram was drawn from. If players stop coming because the evenings grow dark, the same loops are in the diagram, and they still match; the story is what would be wrong.

That a second court is where to act

Not quite. Kim puts the leverage in limits to growth at the limit, and a second court acts there. But that is a leverage point, a hypothesis drawn in its own box; a match places no leverage point.

Activity spaces on Amsterdam’s outskirts, redrawn

Redrawn from Jillian O’Mara, Loes Crielaard, Luc Hagenaars, Karien Stronks and Wilma Waterlander, “Using systems archetypes to understand system behaviour and identify leverage points for change in local obesity prevention in The Netherlands”, Health Promotion International 41(3), daag056 (2026), Table 1, LA2, its causal loop diagram. CC BY 4.0.

Its prefixes Symptomatic solution, Fundamental solution and Side-effect written as roles above the names, and Problem symptom dropped; its dashed lines, its mark for an inverse effect, drawn solid with a −, since a dash here marks a hypothesis; its color left out; spaces aren’t used renamed as an amount, spaces left unused, and the other four names shortened; each loop named; fixes that fail and shifting the burden, the two archetypes its authors name, declared.

Question 1 of 3Its authors name two archetypes, and both are declared. Which loops hold fixes that fail?

B1 and B2, the two balancing loops sharing the lack of adolescent physical activity.

Not quite. Two balancing loops sharing one variable have the shape of escalation and eroding goals, and both match here, within shifting the burden. Fixes that fail has a reinforcing loop, and R1 is the only one.

B1, spaces built, and R1, interest doubted.

Yes. B1 is the fix, through activity spaces on the outskirts; R1 leaves the same spaces through the side effect and comes back to the problem symptom through urban areas that facilitate activity. That way back is a chain of two effects, so fixes that fail sits within shifting the burden, as it does wherever the way back is four effects or fewer.

B2, areas improved, and R1, interest doubted.

Not quite. Fixes that fail’s balancing loop runs through the variable its side effect leaves from, the symptomatic solution. B2 runs through urban areas that facilitate activity, the fundamental solution, and the side effect leaves from the spaces on the outskirts.

Question 2 of 3More impression that spaces won’t raise activity: what does it change, and through which loop?

More activity spaces on the outskirts, through its own effect on them.

Not quite. No effect runs from the impression to the spaces. Its one effect, a −, ends at urban areas that facilitate activity; the spaces rise only as the lack of activity does, around R1.

Nothing in the loops: a side effect sits outside them.

Not quite. R1 runs through it, from spaces left unused to urban areas that facilitate activity: the side effect is the reinforcing loop’s middle, and without it R1 doesn’t close.

Fewer urban areas that facilitate activity, so the lack of activity stays high: R1.

Yes. Its − effect lowers the fundamental solution: spaces left unused read as no interest, and less goes into areas close to home. B2 weakens, the lack of activity stays high, and more spaces go on the outskirts, closing R1.

Question 3 of 3The figure has no delay, as its authors drew none. On which effect does shifting the burden’s delay belong?

Urban areas that facilitate activity → lack of adolescent physical activity.

Yes. Streets, squares and routes to school take years to rebuild, and habits of walking and playing outside follow later: the change in activity comes long after the change in the areas. With that delay, B2 relieves the problem symptom slowly while B1 seems to relieve it at once, and the spaces on the outskirts are built first.

Activity spaces on the outskirts → lack of adolescent physical activity.

Not quite. That is the symptomatic solution’s effect. Shifting the burden’s symptomatic solution relieves at once; a delay there would take away the reason it is reached for first.

Spaces left unused → impression that spaces won’t raise activity.

Not quite. An impression may form over months, and a delay there would be a defensible addition. The archetype’s own delay is the fundamental solution’s, on B2, and the match lacks it.

Exercises

Passing the checks means meeting the brief, not being right.

AR 01Watering a lawn a little every evening

A relief that brings the problem back

Reasoning1 of 5
Polish1 of 5

Every summer evening, Rosa waters her lawn for ten minutes wherever it has turned brown, and by morning the grass is green again: the browner the lawn, the more she waters. Ten minutes wets only the top few centimeters of soil, so over the following weeks the grass keeps its roots there, where the soil dries first: the more evening watering, the faster the grass dries in heat. The faster the grass dries, the browner the lawn in each hot spell.

The brief

Draw the morning's relief as one balancing loop through the brown lawn and the evening watering. checked by the lab
Draw the drying grass's return to the brown lawn as one reinforcing loop. checked by the lab
Mark one delay: the weeks before the watering makes the grass dry faster. checked by the lab
The two loops match fixes that fail, with its delay on the side effect's chain. checked by the lab
Write the symptomatic solution above the evening watering. checked by the lab
Write the side effect above how fast the grass dries. checked by the lab
Add a behavior note. checked by the lab
The note names the relief each morning and the browning that comes back faster. you check this
The brown lawn is drawn once, as the variable the watering relieves and the drying grass makes worse. you check this

Your palette

variable
effect
polarity
delay
loop
reinforcing loop
balancing loop
behavior note
archetype
symptomatic solutiona role, written above its variable's name
side effecta role, written above its variable's name

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Press an empty spot to add a variable and type its name. Drag a variable to move it. Select a variable, an effect or a loop label to change it. Drag a behavior note to move it. Double-click or double-tap a variable, a loop's label or name or a behavior note to edit its words in place, or select it and use Rename or the fields under the canvas.

Nothing selected. Select a variable, an effect, a loop label, a behavior note or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Note N: place a behavior note (press where it goes).
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
P the selected variable's role, in turn: none, then each role this exercise offers
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 13 checks passed; 13 pending.

Draw the morning's relief as one balancing loop through the brown lawn and the evening watering. (Not started)No loop declared yet. Brief: exactly 1 balancing loop.
Draw the drying grass's return to the brown lawn as one reinforcing loop. (Not started)No loop declared yet. Brief: exactly 1 reinforcing loop.
Mark one delay: the weeks before the watering makes the grass dry faster. (Not started)No effects yet. Brief: exactly 1 delay.
The two loops match fixes that fail, with its delay on the side effect's chain. (Not started)No effect has a polarity yet. Brief: fixes that fail, with its delay.
Write the symptomatic solution above the evening watering. (Not started)No variables yet. Brief: exactly 1 symptomatic solution.
Write the side effect above how fast the grass dries. (Not started)No variables yet. Brief: exactly 1 side effect.
Add a behavior note. (Not started)No loop declared yet. Once one is, add a behavior note naming what it predicts.
The note names the relief each morning and the browning that comes back faster. You check this.
The brown lawn is drawn once, as the variable the watering relieves and the drying grass makes worse. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
Each role is the place its variable stands in a match (Not started)No variable has a role yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

Turn on written feedback

Export

One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

AR 02Electric cars and public chargers

Growth held back by what it uses

Reasoning1 of 5
Polish2 of 5

In a country of five million people, electric cars are cheap to run, and their owners tell friends, family and colleagues so: the more electric cars on the road, the more owners' recommendations, and the more recommendations, the more electric cars people buy. Owners without a driveway charge at public chargers, so the more electric cars on the road, the longer the queues at public chargers, and the more public chargers, the shorter the queues. Word of hour-long waits takes months to reach people choosing their next car; then the longer the queues, the fewer electric cars join the road.

The brief

Draw the recommendations as one reinforcing loop through the electric cars on the road. checked by the lab
Draw the queues holding back new electric cars as one balancing loop. checked by the lab
The two loops match limits to growth: a reinforcing loop and a balancing loop sharing one variable. checked by the lab
Mark the months before word of the queues reaches buyers as a delay inside the balancing loop. checked by the lab
The number of public chargers is the constraint: a variable outside both loops, with an effect into the balancing loop. you check this

Your palette

variable
effect
polarity
delay
loop
reinforcing loop
balancing loop
archetype

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Press an empty spot to add a variable and type its name. Drag a variable to move it. Select a variable, an effect or a loop label to change it. Double-click or double-tap a variable or a loop's label or name to edit its words in place, or select it and use Rename or the fields under the canvas.

Nothing selected. Select a variable, an effect, a loop label or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 9 checks passed; 9 pending.

Draw the recommendations as one reinforcing loop through the electric cars on the road. (Not started)No loop declared yet. Brief: exactly 1 reinforcing loop.
Draw the queues holding back new electric cars as one balancing loop. (Not started)No loop declared yet. Brief: exactly 1 balancing loop.
The two loops match limits to growth: a reinforcing loop and a balancing loop sharing one variable. (Not started)No effect has a polarity yet. Brief: limits to growth.
Mark the months before word of the queues reaches buyers as a delay inside the balancing loop. (Not started)No loop declared yet. Brief: a delay on an effect inside a balancing loop.
The number of public chargers is the constraint: a variable outside both loops, with an effect into the balancing loop. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

Turn on written feedback

Export

One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

AR 03A climbing club that hires guides for its trips

A quick relief that holds back a slower one

Reasoning2 of 5
Polish2 of 5

A climbing club of sixty members runs two trips a month, and each trip needs one qualified leader for every six climbers. When a trip is short of a leader, the club hires a mountain guide for the weekend and the trip goes ahead: the more trips short of a leader, the more hired guides, and the more hired guides, the fewer trips short of a leader. Members can qualify to lead trips themselves through courses and logged climbs that take a full season: the more trips short of a leader, the more members training to lead, and a season later, the more members training, the fewer trips short of a leader. Each guided trip shows the members that a guide will be hired: the more hired guides, the more the club relies on them, and the more it relies on them, the fewer members train to lead.

The brief

Draw two balancing loops through the trips short of a leader: one through the hired guides, one through the members training to lead. checked by the lab
Draw the reliance on hired guides closing one reinforcing loop. checked by the lab
The loops match shifting the burden, with its delay on the training's loop. checked by the lab
Write the symptomatic solution above the hired guides. checked by the lab
Write the fundamental solution above the members training to lead. checked by the lab
Write the side effect above the reliance on hired guides. checked by the lab
The side effect is the reliance the hired guides build up, not a second shortage of leaders. you check this

Your palette

variable
effect
polarity
delay
loop
reinforcing loop
balancing loop
archetype
symptomatic solutiona role, written above its variable's name
fundamental solutiona role, written above its variable's name
side effecta role, written above its variable's name

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Nothing selected. Select a variable, an effect, a loop label or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
P the selected variable's role, in turn: none, then each role this exercise offers
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 12 checks passed; 12 pending.

Draw two balancing loops through the trips short of a leader: one through the hired guides, one through the members training to lead. (Not started)No loop declared yet. Brief: exactly 2 balancing loops.
Draw the reliance on hired guides closing one reinforcing loop. (Not started)No loop declared yet. Brief: exactly 1 reinforcing loop.
The loops match shifting the burden, with its delay on the training's loop. (Not started)No effect has a polarity yet. Brief: shifting the burden, with its delay.
Write the symptomatic solution above the hired guides. (Not started)No variables yet. Brief: exactly 1 symptomatic solution.
Write the fundamental solution above the members training to lead. (Not started)No variables yet. Brief: exactly 1 fundamental solution.
Write the side effect above the reliance on hired guides. (Not started)No variables yet. Brief: exactly 1 side effect.
The side effect is the reliance the hired guides build up, not a second shortage of leaders. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
Each role is the place its variable stands in a match (Not started)No variable has a role yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

Turn on written feedback

Export

One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

AR 04Two parks and one maintenance budget

A small lead that a split widens

Reasoning2 of 5
Polish3 of 5

A town of thirty thousand people has two parks, one by the river and one on the hill, and one maintenance budget for both. Each spring the council splits the budget by the two parks' visitor counts from the year before, and the larger a park's share, the better it is mowed, cleaned and repaired that year. The more visitors to the riverside park, the larger the share of the budget to the riverside park, and the larger that share, the more visitors to the riverside park. The more visitors to the hilltop park, the smaller the riverside park's share, and the larger the riverside park's share, the fewer visitors to the hilltop park. In the first year, the riverside park had a few hundred more visitors than the hilltop park.

The brief

Draw the share of the budget to the riverside park as one variable, with two reinforcing loops through it: one through each park's visitors. checked by the lab
The two loops match success to the successful: two reinforcing loops sharing one variable. checked by the lab
Add a behavior note on the gap between the two parks' visitors. checked by the lab
The two loops are drawn as mirror images, one on each side of the share. you check this
In the note: the first year's gap is small, and the split widens it every year after. you check this

Your palette

variable
effect
polarity
loop
reinforcing loop
behavior note
archetype

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Nothing selected. Select a variable, an effect, a loop label, a behavior note or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Note N: place a behavior note (press where it goes).
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 8 checks passed; 8 pending.

Draw the share of the budget to the riverside park as one variable, with two reinforcing loops through it: one through each park's visitors. (Not started)No loop declared yet. Brief: exactly 2 reinforcing loops.
The two loops match success to the successful: two reinforcing loops sharing one variable. (Not started)No effect has a polarity yet. Brief: success to the successful.
Add a behavior note on the gap between the two parks' visitors. (Not started)No loop declared yet. Once one is, add a behavior note naming what it predicts.
The two loops are drawn as mirror images, one on each side of the share. You check this.
In the note: the first year's gap is small, and the split widens it every year after. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

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One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

AR 05Three countries' fleets on one fishing ground

Gains kept by each, losses shared by all

Reasoning3 of 5
Polish3 of 5

Three countries, called here the northern, western and eastern, send fishing fleets to one fishing ground in international waters. Each fleet's owners spend what they earn on more boats: the more northern boats, the more northern earnings, and the more northern earnings, the more northern boats, and the same holds for the western and eastern fleets. Every boat adds to the total catch, and the larger the total catch, the fewer fish are left to breed. The young fish that go unborn would have been caught years later, so only then does the catch per boat fall: the larger the total catch, the smaller the catch per boat, after a delay of years. The larger the catch per boat, the more each fleet earns; and the smaller the catch per boat, the more boats each fleet sends to make up its catch.

The brief

Draw each fleet's boats and earnings as a reinforcing loop, and its boats, the total catch and the catch per boat as another: two for each of the three fleets. checked by the lab
Draw each fleet's boats returning to its earnings through the total catch and the catch per boat as a balancing loop, one for each fleet. checked by the lab
The loops match tragedy of the commons, with its delay on the total catch's effect on the catch per boat. checked by the lab
The total catch is one variable, which all three fleets' boats add to, not one for each fleet. you check this
No effect crosses another where moving a variable would avoid it. you check this

Your palette

variable
effect
polarity
delay
loop
reinforcing loop
balancing loop
archetype

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Nothing selected. Select a variable, an effect, a loop label or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 8 checks passed; 8 pending.

Draw each fleet's boats and earnings as a reinforcing loop, and its boats, the total catch and the catch per boat as another: two for each of the three fleets. (Not started)No loop declared yet. Brief: at least 6 reinforcing loops.
Draw each fleet's boats returning to its earnings through the total catch and the catch per boat as a balancing loop, one for each fleet. (Not started)No loop declared yet. Brief: at least 3 balancing loops.
The loops match tragedy of the commons, with its delay on the total catch's effect on the catch per boat. (Not started)No effect has a polarity yet. Brief: tragedy of the commons, with its delay.
The total catch is one variable, which all three fleets' boats add to, not one for each fleet. You check this.
No effect crosses another where moving a variable would avoid it. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

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Export

One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

CS 10Kelsham Primary School: merging classes to balance the budget

A saving that brings the spending back

Reasoning3 of 5
Polish3 of 5

Kelsham Primary School is paid £4,800 for each pupil, set from the October count before each school year, so its funding falls a year after its roll does: the fewer pupils on roll, the less school funding, a year later, and the less school funding, the more spending above funding. When the school spends more than its funding, the governors merge classes. In 2023, with 108 pupils, they taught Years 3 and 4 as one class and paid four teachers instead of five, saving £52,000 a year at once: the more spending above funding, the more mixed-age classes, and the more mixed-age classes, the less spending above funding. Some parents, Priya Shah among them, would rather each year were taught as a class of its own, as at Brayford Primary School: the more mixed-age classes, the more parents choosing the town school, and the more parents choosing the town school, the fewer pupils on roll. In October 2026 the roll is 88, and Tom Hale, who chairs the governors, proposes teaching Reception with Years 1 and 2.

The brief

Draw the saving as one balancing loop through spending above funding and mixed-age classes. checked by the lab
Draw the families' leaving as one reinforcing loop back to spending above funding. checked by the lab
Mark one delay: the October count, which sets the funding a year after pupils leave. checked by the lab
The two loops match fixes that fail, with its delay on the side effect's chain. checked by the lab
Write the symptomatic solution above its variable. checked by the lab
Write the side effect above its variable. checked by the lab
Declare the archetype the loops match, in one line. checked by the lab
Add a behavior note. checked by the lab
The note names the saving each merger brings at once and the spending that comes back as the roll falls. you check this

Your palette

variable
effect
polarity
delay
loop
reinforcing loop
balancing loop
behavior note
archetype
symptomatic solutiona role, written above its variable's name
side effecta role, written above its variable's name

To draw in the lab, use a tablet or a larger screen. Everything else reads normally here.

Nothing selected. Select a variable, an effect, a loop label, a behavior note or a declared archetype on the canvas, and what you can change shows here.

The tools

Variables V: add a variable (press an empty spot), move one (drag it), rename one (double-click it, or Rename under the canvas), or select anything.
Effects E: draw an effect by dragging from one variable to another.
Loop L: declare a loop by selecting its effects in order, then label and name it.
Note N: place a behavior note (press where it goes).
Archetype K: declare an archetype: press an empty spot, then choose which of the nine.

Keys

R reverse the selected effect
P the selected variable's role, in turn: none, then each role this exercise offers
+− the selected effect's polarity
Delete delete what's selected
Ctrl+Z undo
Ctrl+Shift+Z redo
Esc clear the selection
Enter finish the words you're writing
Esc cancel them

Keys act on the lab you last used, or on the open lab view, and never while you type.

Archetypes the structure matches

Read from the loops and their kinds as drawn, after each change. Nothing here is saved.

No archetype matches yet.

0 of 14 checks passed; 14 pending.

Draw the saving as one balancing loop through spending above funding and mixed-age classes. (Not started)No loop declared yet. Brief: exactly 1 balancing loop.
Draw the families' leaving as one reinforcing loop back to spending above funding. (Not started)No loop declared yet. Brief: exactly 1 reinforcing loop.
Mark one delay: the October count, which sets the funding a year after pupils leave. (Not started)No effects yet. Brief: exactly 1 delay.
The two loops match fixes that fail, with its delay on the side effect's chain. (Not started)No effect has a polarity yet. Brief: fixes that fail, with its delay.
Write the symptomatic solution above its variable. (Not started)No variables yet. Brief: exactly 1 symptomatic solution.
Write the side effect above its variable. (Not started)No variables yet. Brief: exactly 1 side effect.
Declare the archetype the loops match, in one line. (Not started)No variables yet. Brief: exactly 1 declared archetype.
Add a behavior note. (Not started)No loop declared yet. Once one is, add a behavior note naming what it predicts.
The note names the saving each merger brings at once and the spending that comes back as the roll falls. You check this.

Always checked

Each loop's kind matches its − effects (Not started)No loop declared yet.
Loop labels are unique and match their kind (Not started)No loop declared yet.
Every effect has a polarity (Not started)No effects yet.
The structure matches each declared archetype (Not started)No archetype declared yet.
Each role is the place its variable stands in a match (Not started)No variable has a role yet.
No variable's name breaks the more test's three rules (Not started)No variable drawn yet.

Written feedback

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Export

One defensible answer

It opens here once you've drawn at least one variable in the lab above. Your attempt saves as you draw.

Sources

Daniel H. Kim, Systems Archetypes I: Diagnosing Systemic Issues and Designing High-Leverage Interventions (Pegasus Communications, 1992, 2000): the archetypes used as templates, p. 2; Peter Senge’s The Fifth Discipline (1990) as the source of the term, p. 3; fixes that fail and the squeaky wheel, pp. 16–17; Kim’s name for limits to growth and where its leverage lies, pp. 20–21; shifting the burden, and disagreement over which remedy is symptomatic, pp. 22–23; success to the successful and its starting conditions, pp. 24–25; the tragedy of the commons and why its remedy lies above any one user, pp. 26–27.
Lukas Schoenenberger, Alexander Schmid and Markus Schwaninger, “Towards the Algorithmic Detection of Archetypal Structures in System Dynamics”, System Dynamics Review 31, no. 1–2 (2015): 66–85, on algorithms that find archetypes in simulation models.
International Rice Research Institute, “Letting Nature Manage Its Battles”, Rice Today (6 October 2012), on early sprays that kill the brown planthopper’s natural enemies and make its outbreaks ten times more likely.