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BUILD · SCIENCE · Lesson 3 of 10

Where did the water go?

Learning intention

Use input minus collected water to estimate and compare water remaining after drainage.

We add the same amount.

Different amounts drain out.

How much is not collected?

Success looks like

  • Record input and collected volumes with mL units.
  • Subtract collected volume from input to find the amount not collected.
  • Compare samples and explain one reason the result is only an estimate of soil water held.
Retrieval

BUILD · SCIENCE · Lesson 3 of 10

Three links from last time

1. Where can water move through soil?

2. Name one fair-test control.

3. What is 60 minus 20?

I do

BUILD · SCIENCE · Lesson 3 of 10

Account for the added water

Start with the water added.

Subtract the water collected.

Record the difference in mL.

Account for the same 60 mLConstructed worked example. Sixty millilitres were added and 34 millilitres collected after five minutes. The difference is 26 millilitres not collected. With no spills and negligible evaporation and negligible initial water, this is approximately water remaining in the setup.60 mL added34 mL collected26 mL notcollected60 − 34 = 26 mLModel: initial water and losses ignored.
Account for the same 60 mL
Diagram description

Constructed worked example. Sixty millilitres were added and 34 millilitres collected after five minutes. The difference is 26 millilitres not collected. With no spills and negligible evaporation and negligible initial water, this is approximately water remaining in the setup.

I do

BUILD · SCIENCE · Lesson 3 of 10

Be precise about “held”

Water can remain in soil pores.

Some may remain above the soil.

The filter can hold water too.

Not collected does not mean soil onlyA simplified pot showing water above the soil, water in the soil pores, and water held by the filter. All three can contribute to the volume not collected. The illustration is not to scale.Water may still beabove the soil.Some water remainsin soil pores.The filter mayhold some water.Check for standing water, drips, leaks and spills.
Not collected does not mean soil only
Diagram description

A simplified pot showing water above the soil, water in the soil pores, and water held by the filter. All three can contribute to the volume not collected. The illustration is not to scale.

I do

BUILD · SCIENCE · Lesson 3 of 10

Compare equal water budgets

Each starts with 60 mL.

Less collected means more left over.

Always state the time.

Same input, different amounts outConstructed sample data: each sample receives 60 millilitres. After five minutes, A collects 46, B 34 and C 22 millilitres. Equal-length bars show collected volume and the remainder, under the no-spill assumption.Constructed sample data • 60 mL in eachA46 collected14 leftB34 collected26 leftC22 collected38 leftLeft at 5 min; initial water/losses ignored.
Same input, different amounts out
Diagram description

Constructed sample data: each sample receives 60 millilitres. After five minutes, A collects 46, B 34 and C 22 millilitres. Equal-length bars show collected volume and the remainder, under the no-spill assumption.

Which sample has the largest amount not collected?

We do

BUILD · SCIENCE · Lesson 3 of 10

The water-budget team

Read the inputs and outputs.

Choose the correct calculation.

Check with the whole-water bar.

Constructed sample data • no spills • initial water and evaporation ignored
SoilInput (mL)Collected at 5 min (mL)
A6046
B6034
C6022

For B: 60−34, 60+34 or 34−60?

We do

BUILD · SCIENCE · Lesson 3 of 10

Find the overclaim

“C held exactly 38 mL in the soil.”

“C had 38 mL not collected at five minutes.”

Which claim fits the evidence?

Constructed reasoning cards; consider each situation separately
Check cardWhat happened?
PNo spills; same apparatus; no losses assumed
QA puddle remained above the soil
RSome water escaped onto the tray
Hinge

BUILD · SCIENCE · Lesson 3 of 10

Which statement is sound?

Each sample receives 60 mL.

A collects 46 mL; C collects 22 mL.

You do

BUILD · SCIENCE · Lesson 3 of 10

Investigate; record; explain

Choose paper data or a practical.

Choose calculator, writing or spreadsheet.

Use a number and a careful claim.

You do

BUILD · SCIENCE · Lesson 3 of 10

Keep the method matched

Same soil volume and preparation.

60 mL poured over 10 seconds.

Read at 5 minutes from pour start.

Continue within this stage’s shared time.

You do

BUILD · SCIENCE · Lesson 3 of 10

Make a water account

Input minus collected equals not collected.

Compare your three remainders.

Say what your estimate includes.

You do

BUILD · SCIENCE · Lesson 3 of 10

Check the claim before sharing

Have I used mL?

Have I stated 5 minutes?

Have I checked for losses?

Continue within this stage’s shared time.

Review

BUILD · SCIENCE · Lesson 3 of 10

Lundy loop: improve the claim

Share a result or a concern.

Listen for an overlooked location.

Rewrite one class conclusion.

What wording should our class keep?

Exit

BUILD · SCIENCE · Lesson 3 of 10

Close the water account

E1. 60 mL in; 40 mL out. How much not collected?

E2. Where else could water remain?

E3. Why state the time?

My science task sheets

Choose one route with your teacher. Shared evidence and the exit sheet appear in every route. Your work stays here while the page is open; save it before closing.

Water-budget lab • evidence

Constructed sample data. Same 100 cm³ loosely filled starting soil volume, matched moisture, pots/filters. Add 60 mL over 10 seconds. Collect at 5 minutes from pour start. Assume no spills and negligible evaporation and negligible initial water.

SoilInput (mL)Collected at 5 min (mL)
A6046
B6034
C6022

P • Clean run

Same apparatus and method. No spills observed; initial water and evaporation are ignored.

Q • Standing water

A puddle of water remains above the soil at 5 minutes.

R • Spill

Some added water escapes onto the tray and is not collected.

Route 1 • Follow the water

Use the constructed sample data. A calculator or an adult scribe is welcome.

S1. A receives 60 mL and collects 46 mL. Which calculation finds what was not collected?

The calculated amounts not collected are A 14 mL, B 26 mL and C 38 mL. These come from the constructed sample data; they are setup estimates at 5 minutes.

Route 2 • Record and compare

Use the constructed data or actual readings from an approved practical. Write the data source. Optional spreadsheet: put Soil in A1, Input_mL in B1, Collected_mL in C1, Not_collected_mL in D1. In D2 enter=B2-C2 and copy down.

T2: SoilInput(mL)Collected(mL)Not collected(mL)
A
B
C

Route 3 • Test the water account

Use the constructed five-minute dataset on the evidence page.

Constructed spill case:60 mL added; 30 mL collected; 10 mL spilled onto a separate tray. Assume no evaporation or initial water.

Constructed longer test: sample C collects 22 mL by 5 minutes and 30 mL by 10 minutes in total. Input stays 60 mL; no spills; initial water and evaporation ignored.

Exit and reflection

Use words, numbers, a diagram or a spoken response. A calculator is allowed.

Slide 1

TA Brief

Current stage

Objective

Use input minus collected water to estimate and compare water remaining after drainage.

Preparation

Method precautions

Practical alternative

Use the complete constructed dataset and water-accounting diagrams. All core questions can be answered on paper or in a locally created spreadsheet. The dataset assumes no spills, negligible evaporation and negligible initial water; practical results must be labelled separately.

Access and regulation

Supported: Use a calculator, a60-unit strip or adult-scribed number sentence. Pupil selects the correct subtraction and compares completed values; the science remains the same.

Standard: Complete all three water-balance rows and an evidence claim, with one stated limitation. Optional spreadsheet has a taught formula.

Stretch: Evaluate a spill/error case and a longer-drainage result; distinguish the setup estimate from soil-only and plant-available water.

Regulation: Offer a dry recording role or paper task. A five-minute observation can include a quiet seated check-in. No compulsory contact with soil or timed arithmetic contest.

Teacher answers

Retrieval 1–3

1 Connected spaces/pores between particles.2 Any relevant matched condition, input, time, soil volume, starting moisture, packing action, pot/filter or pour duration.3 60−20=40.

Worked water balance

B:60−34=26 mL not collected. Under no-spill, negligible-evaporation and negligible-initial-water assumptions this estimates water remaining in the whole setup, including any water in soil, on top or in the filter.

W1 / operation options

Choose 60−34=26 mL. 60+34=94 adds input and part of that same input, so does not find the remainder.34−60=−26 reverses the direction and is not a valid remainder here.

W2 / cards P, Q, R

The exact-soil claim is too strong because the filter may retain water and water may remain above soil. P supports a setup estimate only. Q shows one non-soil store. R means uncollected water includes a spill, so repeat or account for the measured loss; do not label it all as retained in soil.

Hinge

C has the greater amount not collected at this time:38 mL versus A 14 mL. A’s larger output means its remainder is smaller. A plant-growth conclusion goes beyond the measured balance.

S1–S5

S1 60−46. S2 14 mL. S3 C, 38 mL, greater than 26 and 14. S4 above the soil, in the filter or stuck to apparatus; a spill is a loss outside setup, not a retained store. S5 does not: some water is not inside soil, some soil water is held too tightly, and plant uptake was not measured. Accept one clear reason.

T1–T2

T1 identify constructed data or actual measurement; time 5 min from pour start; control 60 mL input, 100 cm³ soil, 10-secondpour, matched moisture, loose packing action and identical pot/filter. T2 constructed:A 60/46/14, B 60/34/26, C 60/22/38 mL. Actual data may differ and must be used honestly; if output exceeds input, check starting wet apparatus or measurement before claiming negative retention.

T3–T5

T3 C 38>B 26>A 14 mL for sample data; actual data require their own comparisons. T4 “At 5 minutes, C had 38 mL not collected, the largest amount in this test; this estimates water remaining in the setup if no water was lost.” T5 check for spills/leaks, standing water, filter storage, continued drips or substantial evaporation. Any one accurate limitation suffices.

X1–X4

X1 A 14, B 26, C 38 mL; C>B>A. X2 60−30=30 mL not collected; subtract 10 mL spill to estimate 20 mL remaining in the setup. X3 at 5 min 38 mL not collected; at 10 min 30 mL. An additional 8 mL drained between readings. X4 setup includes non-soil water; five/tenminutes is not field capacity; water held can be too tightly bound for roots; plant physiology and soil-air conditions are unmeasured. Accept a suitable concise explanation.

E1–E3

E1 20 mL. E2 filter, above-soil puddle, container surface. E3 more water can drain later, so the measured remainder depends on time; all comparisons need the same time.

R1–R2

Accept careful phrases such as “not collected”, “atfive minutes”, “in this setup” or “assuming no spills”. R2 should be a relevant investigable question, e.g.what happens if drainage time increases; no fixed preferred question.

ICT

D2 formula=B2-C2. With the constructed data rows, A 14, B 26, C 38. Copying the formula down should adjust row references. A learner should check one result by hand or calculator rather than trust formatting alone.

Optional practical

Report actual input/output/time and visible standing water or losses. Input−collected is uncollected water; only under the no-loss approximation does it estimate what remains in the setup. For soil-only storage a different measurement method and correction for apparatus/water outside soil would be needed.

Sources checked for this lesson

Word help

retain
Keep or hold.
input
The water we add.
collected
The water caught after it drains out.
estimate
An approximate value based on measurements and assumptions.
water balance
Accounting for where the added water goes.

Cold Call

Give thinking time. Invite a response by voice, pointing or showing work. A pupil can pass; check in privately when useful.

Pause

Take a quiet pause.

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