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LAUNCH · Science · Week 5

Master: Analysing the Osmosis Practical

Aut1·W5 (Master) — Plot, analyse and evaluate the osmosis core practical.

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 analyse osmosis results with a graph and evaluate the method independently.

✅ Success Criteria

  • I can read the concentration inside the cells from a graph (the zero-change point).
  • I can calculate percentage change and label the axis correctly.
  • I can evaluate the method and suggest one improvement.
🔗 Assessment link: AQA UAS: 'Cells and transport'; 'Analysing and evaluating'.

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

On the graph, point to where the line crosses zero percentage change.

🗺️ Today at a Glance

Three things we do today

1.

Plot and read the graph

2.

Find the zero-change point

3.

Evaluate the method

👩‍🏫 I Do · watch me think

Watch me read the graph — then you evaluate

🧠 Watch me think: Percentage change up the side, concentration along the bottom. The line slopes down and crosses zero at one concentration. THAT crossing point estimates an equivalent solute concentration for the potato tissue under these conditions, because there the mass did not change — no net osmosis. Above it, loss; below it, gain. Now you evaluate: what limited this result, and how would you improve it?

📖 Key definitions

  • analyse — Use the data to find a pattern or a value.
  • evaluate — Judge how good the method or evidence is, and how to improve it.
  • anomaly — A result that does not fit the pattern.
  • isotonic point — The concentration where mass does not change — an estimate of equivalent solute concentration in the tissue.
❌ Common mistake: Evaluate just means say it went well.
✅ Actually: Evaluate weighs strengths AND weaknesses, then gives an improvement. Both sides, then a fix.
🤝 We Do · together

Analyse or evaluate?

Name the skill before you tap.Found 0/5
Read the zero-change concentration off the graph
Say the blotting was inconsistent and suggest a fix
Circle a point that does not fit the trend
Suggest three repeats to improve reliability
Where the line crosses zero

👩‍🏫 I Do 2 · the evidence loop

Evidence loop

🧠 Watch me think: Show-me lesson: you plot the class data, read the zero-crossing, and write a two-line evaluation — one strength, one limitation, one improvement. Mark your OWN evaluation against the board: did you give both sides and a fix? Tick each. Method, never a grade.

Assessor witness · what the adult is watching for

  • Read the cell concentration from the zero-crossing.
  • Calculated and plotted percentage change correctly.
  • Evaluated the method with a strength, a limitation and an improvement.

📸 Capture: Photograph the pupil's plotted graph with the zero-crossing marked and their written evaluation.

🤝 We Do 2 · sort, then write

Strong or weak evaluation?

Sort, don’t guess. Put each card in the right bin.Sorted 0/6
'It went well.'
'Blotting varied, so masses were not fair; blot each the same way.'
'Repeat each concentration three times for reliability.'
'I deleted the odd result.'
'The controls were kept the same, which was good.'
'It was a fun experiment.'
● WEAK
■ STRONG
▲ WRONG
◆ NOT AN EVALUATION

✏️ Independent Work

Your turn — pick your tier

Continue the osmosis record.

Open your Osmosis Practical record. Check sample labels, actual initial/final masses, exposure times and who collected each reading. If staff collected a live setup’s endpoint after the previous lesson, label those readings as staff-collected. Do not leave samples soaking until this lesson just because it is next on the timetable. If a value is missing, keep it pending and use an identified supplied record for today’s analysis.

Today’s 15 minutes: 3 to check provenance and complete a calculation; 7 to plot the assigned points and read only what the graph supports; 2 to check evidence with an adult or partner; 3 to write, dictate or annotate a strength, a limitation and an improvement. Keep unfinished analysis for completion with your adult. No new incubation or sample preparation is scheduled in this session.

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.

15:00

◆ Supported

Plot four given points, mark the zero-crossing, and complete an evaluation sentence from the word bank.

▲ Standard

Plot the class data, read the cell concentration, and write a strength, a limitation and an improvement.

★ Stretch

Plot the data, estimate the external no-net-mass-change concentration, identify any anomaly, and write a full evaluation with a justified improvement.

🔁 Lundy Loop

Where what you say changes something

This is where your voice changes what happens next.

🛡 Space

Graph work and criticism can feel exposing. Evaluating a method is judging the METHOD, never the person who ran it.

🗣 Voice

If you think the class data is unreliable, say why — a reasoned challenge is exactly what evaluate rewards.

👂 Audience

Your graph and evaluation go into the Topic 1 folder with their data source and the practical steps actually completed. Supplied-data analysis does not replace any remaining pupil practical work.

⚙ Influence

The class agrees which improvement we would actually make if we ran it again.

🎫 Exit Ticket

Before you go

◆ Supported

What does the point where the graph crosses zero tell you?

an estimate of the tissue’s equivalent solute concentration under these conditions

Slide 1/10
🏅📸✍️

Master: Analysing the Osmosis Practical — banked!

LAUNCH Science · Week 5 ✅

I can read the concentration inside the cells from a graph (the zero-change point). I can calculate percentage change and label the axis correctly. I can evaluate the method and suggest one improvement.
⏸ MID-POINT PEER CHECK

Pens down — quick partner check!

📣 Show your partner where you’re up to. Check together against today’s success: I can read the concentration inside the cells from a graph (the zero-change point). and I can calculate percentage change and label the axis correctly.. If something’s missing, help them add it — kindly.

Optional check: use up to two minutes of the independent-work allocation. Manual pause is available if you need more time.

Lesson resources · W5L3

LAUNCH Science · W5L3 · lesson resources

Keep the unusual result

Choose one shared task or resource within the current lesson stage. Keep the lesson’s 40-minute timetable and 15-minute independent work.

Friday analysis: use the labelled sample dataset below, or a clearly identified set of measurements collected during the arranged practical. Keep raw results visible. Sample-data analysis does not record practical completion.

We Do · Keep the unusual result

Illustrative samples. Calculate the means; estimate where change is zero.

Sucrose / mol dm⁻³Repeat 1 / %Repeat 2 / %Repeat 3 / %
0.0182022
0.2101214
0.4024
0.6−10−8−6
0.8−18−20−22

An extra repeat at 0.6 gives +9%. What should happen before excluding it?

Discuss, point, write or dictate your first reason. Use one example first; extend only if there is time.

Reveal shared reasoning after an attempt

Means: +20, +12, +2, −8, −20%.
Nearest crossing: 0.4 + (2 ÷ 10) × 0.2 ≈ 0.44 mol dm⁻³.
Retain and flag +9%; check the record and method before deciding. With it, the 0.6 mean is −3.75%.

This page keeps your writing while it stays open. It does not save or send it.

Model explanation and diagram
Scientific visual for this lesson A local vector model used to support observation and reasoning. Labels and explanations are supplied in the lesson. 0% changeraw values remain visible; crossing is an estimate
A model illustration. Use the stated measurements for calculations.

Keep the raw data visible. Flag unusual values and investigate. Never delete a value simply because the graph looks tidier without it.

Watch for: Between +12% at 0.2 and −8% at 0.6, straight-line interpolation gives 0.44 mol dm⁻³, not the midpoint 0.4.

Give a smaller support cue

Find each mean: add the repeats and divide by their number. Describe the trend. Keep unusual results visible and explain any choice to leave one out.

Optional video · Osmosis

Watch for: Which substance moves, through what, and in which net direction?

Use a short relevant extract within I Do, then pause for an explanation. The clip replaces part of the modelling time.

Open the freesciencelessons video in a new tab

No-video version · use the same question
Scientific visual for this lesson A local vector model used to support observation and reasoning. Labels and explanations are supplied in the lesson. water crosses; represented solute is blocked

Water moves through a partially permeable membrane. Its net movement is from a more dilute solution to a more concentrated solution.

Internet is needed for the optional clip. It is concept teaching; viewing it is not completion of a practical.