Learn

Learning preferences

Make learning more comfortable. Changes apply immediately.

Enlarges page content, including diagrams and their labels. You can also use your browser’s zoom.

Choose the colours that are easiest for you to distinguish. Applies to lesson diagrams and lab plots. Labels, shapes, hatching and line patterns also distinguish meanings. Source photographs and raw image brightness stay unchanged; mask-only views are available for image overlays.

ExampleComparisonSample link

Saved in this browser on this device. Preferences are separate from progress backups.

SCIENCE · INVESTIGATE AND EXPLAIN

Draw a water-system boundary

Distinguish stores, actual flows and unmet requests in a daily water ledger.

Learning outcome: Draw the reservoir boundary and conserve water without treating unmet demand as an outflow.

Starting recap

Initial storage is 40 m3; capacity is 100 m3; inflow, spill, release and service share daily bins.

All lessons are open directly. Your saved experiments remain when you leave and return.

Try

Regular inflow with release 5 gives day-one storage 40 + 20 - 5 - 20 = 35 m3.

Open the experiment

Predict

Does an unmet service request belong on the water-outflow arrow?

Experiment

Sketch the boundary, compute two successive days and capture a recipe with units and policy order.

Allocate a bounded reservoir under stress

Fictional water-allocation policy · separate observed river record · Original fictional reservoir, capacity 100 m³ and initial storage 40 m³. Each daily bin receives all its supplied inflow, spills above capacity, prioritizes the requested downstream release, then supplies service demand from remaining water. No evaporation, groundwater, within-day hydraulics or forecast. Release targets are policy assumptions, not ecological adequacy thresholds. Unmet requests are not water fluxes. This model is not calibrated to the separate USGS river record.

Reset keeps your prediction, captures and practice history.

One reservoir, two requests and a fixed order

Regular inflow; service request 20 m³/day. This fictional store starts with 40 m³ and holds at most 100 m³. The requested controlled downstream release is 5 m³/day. The service request is 20 m³/day. These are supplied teaching conditions, not a real reservoir forecast or recommended ecological flow.

Predict before comparing: if you increase the release request under the same inflow scenario, what happens to service and storage? Treat your preferred allocation as a stated choice; the arithmetic does not decide whose needs should take priority.

  1. Receive the whole day's supplied inflow into the starting store.
  2. Spill any volume above 100 m³ before either requested allocation.
  3. Prioritize controlled downstream release, capped by the water available.
  4. Supply school/community service from the remaining water; retain the remainder for the next day.

This daily event order is a policy and timing assumption. It does not resolve within-day hydraulics. Changing the order could change spill or service. Evaporation, groundwater exchange and other losses are omitted.

Stored volume (m³): initial state and end-of-day snapshots020406080100Capacity 100 m³01234567Day 0 is initial storage; days 1–7 are after allocationLines guide the eye between snapshots; they are not within-day flow predictions.

Close the water ledger

Across seven days: 40 initial + 140 inflow = 0 spill + 35 controlled release + 140 service supplied + 5 final storage, all in m³. Balance residual: 0 m³.

Spill and controlled release both leave the store, but their timing and consequences need not be equivalent. More released water is not, by itself, evidence that ecological needs are met. Unmet requests are comparisons against a target, not additional water leaving the store.

Event order left to right; every quantity is m³ within the stated daily bin
DayStartInflowBefore spillSpillAfter spillControlled releaseAfter releaseService suppliedEndBalance residual
140206006055520350
235205505555020300
330205005054520250
425204504554020200
520204004053520150
615203503553020100
71020300305252050

Keep requests visible when water runs short

All volumes in m³; actual fulfillment plus shortfall equals the request
DayRelease requestedRelease actualRelease shortfallService requestedService suppliedUnmet service
155020200
255020200
355020200
455020200
555020200
655020200
755020200
Seven-day totals353501401400
Check a matched comparison and a timing counterexample

Worked comparison, separate from the current selection: under regular inflow, requesting 5 m³/day releases 35 m³, supplies all 140 m³ of service and leaves 5 m³. Requesting 10 m³/day releases 70 m³, supplies 110 m³ of service and leaves zero; unmet service rises to 30 m³. One reported indicator improves while another worsens. Choosing between these cases needs objectives and evidence beyond this ledger.

For the pulse case, day one begins with 40 m³ and receives 80 m³. The resulting 120 m³ exceeds capacity, so 20 m³ spills before allocations. Supplying service first would be a different timing model. Do not interpret the daily snapshot line as evidence that this pulse arrives gradually.

Transfer: keep the requested release at 5 m³/day and compare regular inflow with dry stress, then with higher service demand. Identify which input changed, show the complete water balance, and state one additional observation needed before proposing a real intervention. The separate USGS streamflow record is an observation audit; it does not calibrate these inputs or establish permitted withdrawals.

Final storage 5 m³; service supplied 140 of 140 m³ requested; unmet service 0 m³.

40 + 140 inflow = 0 spill + 35 controlled release + 140 service + 5 storage (m³). Requested controlled release 35 m³; release shortfall 0 m³. Priority and daily event order are assumptions, not a claim about the best policy.

Captures preserve recipes and replay their calculated results. They are synthetic model evidence, not physical measurements.

Understand

Draw the boundary before recommending a change

A school wants reliable water service while people downstream want water left in the river. Before ranking plans, decide what your diagram includes. The investigation begins with a fictional reservoir, not a measured school supply or a calibrated Potomac River model. Your first action is to draw a box around the reservoir and label every permitted crossing.

Put storage inside the box. Draw inflow entering and three arrows leaving: spill, controlled downstream release and supplied service. An arrow represents a volume during a stated interval; storage represents water present at a boundary time. Mixing those two kinds of quantity can produce a convincing-looking but incorrect budget.

Make the accounting assumptions visible

The reservoir capacity is 100 m³ and initial storage is 40 m³. Seven daily bins are calculated. Requested downstream release can be 0, 5 or 10 m³ each day. The regular schedule supplies 20 m³ of inflow per day and requests 20 m³ of service per day. One cubic meter is 1,000 liters, so initial storage is 40,000 liters. The chosen scale is a teaching assumption, not an estimate of an actual reservoir.

Within each bin, the model receives the whole inflow, spills any volume above capacity, fulfills downstream release up to available water, then supplies service from what remains. Write that order beside your arrows. It represents an operating policy and timing approximation, not a physical requirement that all reservoirs follow. It does not resolve hourly inflow, outlet hydraulics or simultaneous operations.

Evaporation, groundwater exchange and direct rainfall on the reservoir are omitted. Do not quietly insert an additional loss when checking this model. Instead, state which omitted process would require a new term if the boundary were used for a real study. USGS water-budget guidance provides the conservation framework; it does not validate these fictional constants.

Close one day’s ledger

Select regular inflow and a requested release of 5 m³/day. Before reading the result, calculate the first day. Starting storage plus input is 40 + 20 = 60 m³, below capacity, so spill is zero. Release removes 5 and service removes 20, leaving 35 m³.

The balance is start + inflow = spill + actual release + supplied service + end. For this day, 40 + 20 = 0 + 5 + 20 + 35. Every term is a volume for the same bin or its boundary time. Dividing selected terms by one day can produce average rates, but a rate must not be added directly to a stored volume.

Repeat for day two. Capture the settings and annotate your drawing with the second day’s starting storage. The previous endpoint becomes the next start; initial storage is not a new input every day. Explain that connection in your reflection rather than listing seven disconnected equations.

Keep unmet requests outside the water arrows

A request is not necessarily a delivered flow. If only 3 m³ remains for service and demand is 20, supplied service is 3 and unmet service is 17. The 17 measures a shortfall against an objective. It is not another 17 m³ leaving the reservoir.

Service supplied crosses our reservoir boundary, but the model does not track its later destination. Therefore it does not identify how much is consumed, returned downstream or stored elsewhere. Withdrawal, consumption and return flow require a wider boundary and additional observations. Likewise, spill is not interchangeable with controlled release or proven ecological benefit.

Transfer: test an unfamiliar ledger

A separate fictional day starts with 12 m³, receives 8, releases 5 and supplies 10, with no spill. Find final storage. If requested service was 14, identify the unmet amount and decide whether it belongs in the conservation equation. Make your calculation before opening the public check.

Check the system-boundary transfer

Final storage is 12 + 8 − 5 − 10 = 5 m³. Unmet service is 14 − 10 = 4 m³. Conservation reads 12 + 8 = 5 + 10 + 5, without adding the unmet request as an outflow. This original arithmetic checks boundary reasoning, not real supply reliability or independently assessed mastery.

Apply

Unmet service is:

Public practice checks a specific claim. It does not establish independent mastery.

Identify omitted processes and distinguish withdrawal from consumption or return flow.

Continue

Completion requires a saved prediction, at least one capture and a reflection. Presence checks do not grade your reasoning.

Skipping retains experiments and awards no mastery.

Next: Compare reservoir allocation policies
Save a science backup or import one

Science work is stored locally in this browser, separately from mathematics and AI. It does not sync automatically. Use this science-only backup; this checkout's older all-subject export does not include science.

A legacy file is available only when the complete snapshot fits the 36 MB limit. For larger snapshots, prepare a complete file set below; never discard notebooks to make a smaller file.

Matching imported notebook drafts replace their current drafts. Omitted lessons and known first attempts remain. Export your current work first if you want to retain both drafts.

Complete file sets and course backups

A file set can hold more work than one science file. Keep its manifest and every part together. Each file is limited to 36 MB. This format needs this version of LearnAI or a compatible newer version; older versions can use only the legacy single-file backup above.

The set includes every saved science course and global continuation at this moment. Later edits need a new export. A conflicting tab exports its own visible work, which may differ from saved work in another tab.

0 file(s) selected. File order and filenames do not determine identity. Missing, changed or conflicting parts block the entire restore; no good part is applied by itself.

Science storage: loading. No account or remote computation is required.