LAUNCH · Science · Week 5

Use: Osmosis Core Practical

Aut1·W5 (Use) — Investigate osmosis with the core practical; calculate % change.

Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1Pearson Edexcel GCSE (9–1) Biology 1BI0 (Foundation, grades 1–5); GCSE Combined Science 1SC0 F where appropriate; AQA UAS science units

🎯 Learning Objective: I can carry out the osmosis core practical and calculate the percentage change in mass.

✅ Success Criteria

I can name the control variables in the core practical.
I can calculate percentage change in mass.
I can explain my results in terms of water concentration.

🔗 Assessment link: AQA UAS: 'Cells and transport'; 'Carrying out a practical investigation'.

LAUNCH · one 40-minute session. Title orientation is untimed; keep the full 15-minute independent task.

Teacher timing and core practice

40-minute session: Arrival 3; overview 1; I Do 1 4; We Do 1 4; I Do 2 3; We Do 2 4; independent work 15; feedback and next step 3; exit 3. Title orientation is untimed. The optional two-minute evidence check sits inside independent time. Keep extra practice available; use the core question, a contrasting example and a recheck before extending.

🖨 Teacher print tools

Resources · shared task, PDFs and video

🚪 Arrival · start this as you come in

Arrival task — pick your tier

◆ Supported

From the word bank, write the one thing we deliberately change in this practical.

▲ Standard

Name two variables we must keep the same in the osmosis practical.

★ Stretch

Write the percentage change equation and state which mass you divide by.

🗺️ Today at a Glance

Three things we do today

1.

Set the controls

2.

Run and weigh

3.

Calculate % change

👩‍🏫 I Do · watch me think

Watch me set it up — then you run it

🧠 Watch me think: Same source of potato, comparable dimensions, the same exposure interval and consistent blotting are controls. Record initial mass with the balance’s available precision before immersion. Today we either measure prepared samples after their full stated exposure, use an identified complete record, or start a live set with a named endpoint collector. A live set stays for its full planned interval; a missing final mass remains pending. We keep actual times and say who collected each reading.

📺 Optional clip — Oak National Academy · ad-free · Foundation Edexcel: Osmosis & sugar concentration on plant tissue — required practicalWatch the practical set-up before you run it · needs internet · captions on · this lesson teaches fully without it.

The core practical: one potato, one variable — the concentration. Record the ◆ initial mass first, blot every cylinder the same way, then find the % change.

📖 Key definitions

core practical — A required experiment you must be able to describe and analyse.
control variable — Something kept the same so the test is fair.
percentage change — (change ÷ original) × 100.
initial mass — The mass recorded BEFORE the potato goes in the solution.

❌ Common mistake: A mass loss means the experiment failed.
✅ Actually: A loss is a valid result — it tells you the outside solution was more concentrated than inside.

🤝 We Do · together

Predict the direction

Say gain, lose or no change before you tap.Found 0/5

Potato in pure water

Potato in very concentrated sugar solution

Potato in a solution matching its own cells

Which mass do you divide by?

Result is −8%. Did it gain or lose?

👩‍🏫 I Do 2 · the evidence loop

Evidence loop

🧠 Watch me think: Worked example, not a pupil result: initial 4.20 g, final 4.62 g. Change = +0.42 g. Percentage = 0.42 ÷ 4.20 × 100 = +10%. Divide by the INITIAL mass and keep the sign. Use only actual or identified supplied masses in your own record; missing endpoints stay pending.

Assessor witness · what the adult is watching for

Named the control variables.
Recorded the practical steps actually performed, the mass source and any steps still pending; supplied-data analysis is not a full pupil-run practical.
Calculated percentage change dividing by the initial mass.

📸 Capture: Keep the pupil’s dated table with available measurements, percentage changes, sample/source IDs and pending endpoints clearly marked. Record the operator and endpoint collector.

🤝 We Do 2 · sort, then write

Explain the result

Sort, don’t guess. Put each card in the right bin.Sorted 0/6

Gained mass in pure water

Lost mass in strong sugar solution

Dividing by final mass

Dropping the minus sign

Sugar moved into the potato

No change at the matching concentration

● Water moved IN

■ Water moved OUT

▲ ERROR

◆ NOT TRUE

○ CORRECT

✏️ Independent Work

Your turn — pick your tier

Choose today’s route with your adult.

Prepared samples or recorded data: use samples whose stated exposure has finished, with their actual initial masses, solution labels and start/end times, or a clearly identified teacher-supplied record. Check who measured each value. Measure final masses only when your adult confirms the exposure is complete. Do not invent a missing value.
Live setup: record your sample labels, initial masses and start times today. Your adult must name who will collect the endpoint after the method’s full interval, including if it falls after this lesson. If no collector is available, use the prepared route. A 30-minute exposure is never shortened to fit this 15-minute task.

Today’s 15 minutes: 3 to check the route, controls and source; 8 to measure/record prepared samples or set up your live samples; 2 to check one entry with an adult or partner; 2 to calculate one available pair or practise with the labelled worked example. Carry unfinished calculations, the full graph and evaluation into Analysing the Osmosis Practical. Record who did each practical step; data analysis alone is not a completed pupil-run core practical.

15 minutes. Choose the tier your adult rings for you.

Use the task time to work, check and improve: reserve up to two of these 15 minutes for an evidence check with your adult or a partner, then act on one useful point. Point, say, sign, demonstrate, write or use an agreed scribe. Manual pause stays available.

◆ Supported

Use the pre-drawn table for two prepared concentrations or two identified recorded rows. Check labels and source; record available masses and calculate percentage change with the printed formula. For live setup, record initial masses/start times and leave final values pending until the named collector returns them.

▲ Standard

Use today’s prepared-sample, identified-data or live-setup route. Keep the full class concentration-range table, record available values with their source and calculate the completed pairs. Carry pending readings and unfinished calculations into the linked Evaluate lesson; do not fill gaps with predictions.

★ Stretch

Check the controls and provenance across the full class range and calculate available percentage changes. Identify what is pending or needs a repeat. Carry the full graph and its justified zero-change estimate into the linked Evaluate lesson; do not invent points to complete the graph.

🔁 Lundy Loop

Where what you say changes something

This is where your voice changes what happens next.

🛡 Space

The prepared route has already completed its stated exposure. A live setup needs the full planned interval and a named endpoint collector; today’s 15-minute work block is not the whole incubation. You can measure, direct, record or calculate through an agreed route.

🗣 Voice

If your result disagrees with the class trend, we look at your method before your number.

👂 Audience

Your labelled record goes into the Topic 1 folder. Staff identify completed practical steps, analysis and what still needs to be carried out.

⚙ Influence

Staff set the consistent blotting method. Pupils can identify a control problem or request a workable role; the adult records what changes before the next run.

🎫 Exit Ticket

Before you go

◆ Supported

Which mass do you divide by to find percentage change?

the initial mass

▲ Standard

A cylinder goes from 5.00 g to 4.50 g. Calculate the percentage change.

−10%

★ Stretch

Explain why a potato in concentrated sugar solution loses mass.

Water concentration outside is lower than inside, so water leaves the cells by osmosis through the partially permeable membrane.

Knowledge Organiser — Use: Osmosis Core Practical

LAUNCH · Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1 · Week 5

Key word	What it means
core practical	A required experiment you must be able to describe and analyse.
control variable	Something kept the same so the test is fair.
percentage change	(change ÷ original) × 100.
initial mass	The mass recorded BEFORE the potato goes in the solution.
blot	To dab dry the same way every time before weighing.

Key facts

percentage change in mass = (final mass − initial mass) ÷ initial mass × 100
Divide by the INITIAL mass, not the final — the classic dropped mark.
Potato in pure water GAINS mass; potato in concentrated sugar solution LOSES mass.
A negative percentage change means the sample lost mass — keep the minus sign.
Controls: same potato, same size cylinder, same time, blotted the same way. Only concentration changes.

Success criteria

I can name the control variables in the core practical.
I can calculate percentage change in mass.
I can explain my results in terms of water concentration.

Session plan: 40-minute session: Arrival 3; overview 1; I Do 1 4; We Do 1 4; I Do 2 3; We Do 2 4; independent work 15; feedback and next step 3; exit 3. Title orientation is untimed. The optional two-minute evidence check sits inside independent time. Keep extra practice available; use the core question, a contrasting example and a recheck before extending.

Choose today’s route with your adult.

Prepared samples or recorded data: use samples whose stated exposure has finished, with their actual initial masses, solution labels and start/end times, or a clearly identified teacher-supplied record. Check who measured each value. Measure final masses only when your adult confirms the exposure is complete. Do not invent a missing value.
Live setup: record your sample labels, initial masses and start times today. Your adult must name who will collect the endpoint after the method’s full interval, including if it falls after this lesson. If no collector is available, use the prepared route. A 30-minute exposure is never shortened to fit this 15-minute task.

Osmosis record and handover

Route: prepared samples / supplied record / live setup. Source or sample ID: __________. Initial measurer: __________. Endpoint collector: __________. Exposure required: __________. Start time(s): __________. Due time(s): __________. Actual end time(s): __________. Final measurer: __________.

Record only observed/supplied values with units. Mark missing values as pending. Keep the initial and final masses beside each sample label, calculate percentage change, and keep this record for the linked Evaluate lesson. Staff record completed pupil steps separately from demonstrations and supplied-data analysis; arrange any remaining practical participation.

Use: Osmosis Core Practical

Name: ____________________ Tier ringed by adult: ◆ Supported ▲ Standard ★ Stretch Date:

Learning objective

I can carry out the osmosis core practical and calculate the percentage change in mass.

Today at a Glance

Set the controls
Run and weigh
Calculate % change

Arrival task

From the word bank, write the one thing we deliberately change in this practical.

Name two variables we must keep the same in the osmosis practical.

Write the percentage change equation and state which mass you divide by.

We Do — Sort each card into the right group

Gained mass in pure water → ______________________________

Lost mass in strong sugar solution → ______________________________

Dividing by final mass → ______________________________

Dropping the minus sign → ______________________________

Sugar moved into the potato → ______________________________

No change at the matching concentration → ______________________________

WAGOLL

Worked example, not pupil measurements: the potato in pure water gained mass because the water concentration outside the cells was higher than inside, so water moved in by osmosis through the partially permeable membranes. Example percentage change = (4.62 − 4.20) ÷ 4.20 × 100 = +10%.

Scaffolding — ◆ Supported

Adult notes — access & sensory
Before class, staff prepare samples/apparatus and choose a feasible route. Prepared samples need authentic initial masses and exposure records; supplied data need a source. A live setup needs a named endpoint collector after the full planned interval, including after this lesson if necessary. Do not shorten the exposure or claim analysis alone completes the pupil-run practical. Record handling, measuring, recording and analysis separately.

Sentence stems

Worked example, not a pupil result: initial 4.20 g, final 4.62 g. Change = +0.42 g. Percentage = 0.42 ÷ 4.20 × 100 = +10%. Divide by the INITIAL mass and keep the sign. Use only actual or identified supplied masses in your own record; missing endpoints stay pending.

Word bank

core practical, control variable, percentage change, initial mass, blot

Scaffolding — ▲ Standard

Sentence stems

Word bank

core practical, control variable, percentage change, initial mass, blot

Scaffolding — ★ Stretch

Sentence stems

Word bank

core practical, control variable, percentage change, initial mass, blot

Independent Work — ◆ Supported

Task: Use the pre-drawn table for two prepared concentrations or two identified recorded rows. Check labels and source; record available masses and calculate percentage change with the printed formula. For live setup, record initial masses/start times and leave final values pending until the named collector returns them.

Independent Work — ▲ Standard

Task: Use today’s prepared-sample, identified-data or live-setup route. Keep the full class concentration-range table, record available values with their source and calculate the completed pairs. Carry pending readings and unfinished calculations into the linked Evaluate lesson; do not fill gaps with predictions.

Independent Work — ★ Stretch

Task: Check the controls and provenance across the full class range and calculate available percentage changes. Identify what is pending or needs a repeat. Carry the full graph and its justified zero-change estimate into the linked Evaluate lesson; do not invent points to complete the graph.

Exit Ticket

A cylinder goes from 5.00 g to 4.50 g. Calculate the percentage change.

Assessor Witness Statement

Pearson Edexcel GCSE (9–1) Biology 1BI0 (Foundation, grades 1–5); GCSE Combined Science 1SC0 F where appropriate; AQA UAS science units
Records what was observed, and at which level of independence.

Pupil	____________________
Lesson	Use: Osmosis Core Practical — LAUNCH Science · Week 5
Date	____________________

Observed in this lesson

☐ Named the control variables.

☐ Recorded the practical steps actually performed, the mass source and any steps still pending; supplied-data analysis is not a full pupil-run practical.

☐ Calculated percentage change dividing by the initial mass.

Assessor comment

Ring the tier the pupil actually worked at

◆ Supported

▲ Standard

★ Stretch

Assessor name ______________ Role ____________ Signature ______________ Date ________

Lundy Loop

Space: The prepared route has already completed its stated exposure. A live setup needs the full planned interval and a named endpoint collector; today’s 15-minute work block is not the whole incubation. You can measure, direct, record or calculate through an agreed route.

Voice: If your result disagrees with the class trend, we look at your method before your number.

Audience: Your labelled record goes into the Topic 1 folder. Staff identify completed practical steps, analysis and what still needs to be carried out.

Influence: Staff set the consistent blotting method. Pupils can identify a control problem or request a workable role; the adult records what changes before the next run.

Closing the loop: this one ends on paper — your own hand, or your words scribed by an adult. Saying it aloud starts the loop; writing it is what closes it. Pass is always allowed.

What I said, and what it changed:

Use: Osmosis Core Practical — Feedback Sheet

Keep with your portfolio.

Pupil name:	Date:
WWW (What Went Well):
EBI (Even Better If):
Level worked at: Supported / Standard / Stretch	Evidence filed: Yes / Not yet
Pupil response — my next step:

Solution	Initial / g	Final / g
Water	4.00	4.40
0.4 mol dm⁻³ sucrose	4.00	4.00
0.8 mol dm⁻³ sucrose	4.00	3.60

Use: Osmosis Core Practical

✅ Success Criteria

🖨 Teacher print tools

Arrival task — pick your tier

◆ Supported

▲ Standard

★ Stretch

Three things we do today

1.

2.

3.

Watch me set it up — then you run it

📖 Key definitions

Predict the direction

Evidence loop

Explain the result

Your turn — pick your tier

◆ Supported

▲ Standard

★ Stretch

Where what you say changes something

🛡 Space

🗣 Voice

👂 Audience

⚙ Influence

Before you go

◆ Supported

▲ Standard

★ Stretch

Use: Osmosis Core Practical — banked!

Pens down — quick partner check!

Knowledge Organiser — Use: Osmosis Core Practical

Key facts

Success criteria

Osmosis record and handover

Use: Osmosis Core Practical

Learning objective

Today at a Glance

Arrival task

We Do — Sort each card into the right group

WAGOLL

Scaffolding — ◆ Supported

Sentence stems

Word bank

Scaffolding — ▲ Standard

Sentence stems

Word bank

Scaffolding — ★ Stretch

Sentence stems

Word bank

Independent Work — ◆ Supported

Independent Work — ▲ Standard

Independent Work — ★ Stretch

Exit Ticket

Assessor Witness Statement

Lundy Loop

Use: Osmosis Core Practical — Feedback Sheet