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Lesson overview

LAUNCH · GCSE Biology · Week 9 · Explore

Mitosis Sequence: Chromosome Evidence

Sequence outcome: Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 2 · specification point 2.1 · mitotic sequence and chromosome evidence.

🎯 Learning objective: I can identify and sequence stages of the cell cycle from diagrams or micrographs, justify stage decisions with visible chromosome evidence, and evaluate uncertainty in snapshot data.
✅ Success criteria
  • Distinguish a visible observation from an inferred cell-cycle stage.
  • Identify interphase, prophase, metaphase, anaphase, telophase and cytokinesis using defensible evidence.
  • Calculate a simple mitotic index and state why a single field of view gives limited evidence about a tissue.
Arrival · previous learningStarter · observe / predictI Do · model the reasoningWe Do · hinge & responseI Do 2 · connect / extendWe Do 2 · scientific model / dataIndependent · evidence & transferExit · receive and use the response
🧪 Microscope Evidence Desk: identify a stage from what is visible, not from guesswork⏱ 40 minutes📍 C39 only🔁 Live Lundy loop↺ Retry without penalty
🔬OBSERVEsay what is visible🧬IDENTIFYstage + evidence📊COUNTsample, not certainty
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 3 min
🚪 Arrival · previous learning
Retrieve only what has already been taught
  1. Last lesson: interphase prepares and copies DNA before mitosis.
  2. Last lesson: prophase condenses, metaphase aligns, anaphase separates and telophase reforms nuclei.
  3. Last lesson: cytokinesis divides the cytoplasm and membrane.
  4. Lead-in: darkness alone is not enough to identify a stage; chromosome arrangement provides stronger evidence.
New to this class, absent, or not sure? Everything needed is in the retrieval box above. Read it, point to it or ask a familiar adult to read it exactly.
◆ Supported
  1. Match chromosomes lined across the middle to metaphase.
  2. Match two separating chromosome groups to anaphase.
  3. Point to the stage before mitosis: interphase.
  4. Lead-in: circle the chromosome clue in one labelled image.
▲ Standard
  1. State one visible clue for metaphase and one for anaphase.
  2. Distinguish observation from inference in: dark bodies are visible, so this may be prophase.
  3. Place telophase before or after anaphase.
  4. Lead-in: explain why an image angle could make stage identification uncertain.
★ Stretch
  1. Explain why condensed chromosomes are easier to distinguish than uncondensed chromatin.
  2. Identify two stages that could be confused in an unclear snapshot.
  3. Predict why many root-tip cells may appear to be in interphase.
  4. Lead-in: state what a stage count can and cannot reveal about time.
LAUNCH response routes
📝 write / edit🗣 structured verbal📏 measure / calculate📊 graph / interpret🧪 practical / demonstrate↺ re-attempt

Access changes the response route, not the GCSE Biology entitlement.

🔊 Read-aloud route: a familiar adult may read the task exactly while the text remains visible. No device voice or media permission is required.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 4 min
🌱 Starter · observe / predict

A micrograph shows condensed chromosomes arranged in a narrow band across the cell centre, with no two separated groups. Which stage is best supported?

LOCAL VISUAL HOOK · FRAME 1
Frame 1: first DESCRIBE only what is visible.
Notice first. Explain after you commit.
LOCAL VISUAL HOOK · FRAME 2
Frame 2: identify the chromosome arrangement, not just image darkness.
Notice first. Explain after you commit.
LOCAL VISUAL HOOK · FRAME 3
Frame 3: make the stage inference and cite the observation that supports it.
Notice first. Explain after you commit.

Commit one first idea. Predictions are held, not marked. Pointing, selecting, saying or signing all count.

QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 4 min
👩‍🏫 I Do · model the reasoning

Make the first scientific idea visible

CONDENSEshorter and more visibleto coil genetic material into compact chromosomes that can be distinguished during mitosis
SISTER CHROMATIDcopied chromosome halfone of two identical DNA copies joined together after chromosome replication
MITOTIC INDEXfraction visibly dividingthe number of cells observed in mitosis divided by the total number of cells observed

WHAT THIS MODEL HELPS US SEE

Use OBSERVATION → STAGE INFERENCE → REASON → LIMIT. For a count, show numerator, denominator and whether the answer is a fraction, decimal or percentage.

WHAT THIS MODEL DOES NOT SHOW

A micrograph is a two-dimensional snapshot of a three-dimensional, continuous process. Cell proportions can estimate relative stage occupancy only under assumptions and do not directly reveal the duration of an individual cell's stage.

Step 1

Write an observation without a stage name: condensed dark structures form one band near the centre. This statement reports visible evidence.

Step 2

Add the inference: the cell is most likely in metaphase because copied chromosomes align near the equator before separation.

Step 3

Check neighbouring stages: a scattered condensed group better supports prophase, while two separating groups better support anaphase.

Word help keeps the scientific term visible and adds a plain-language bridge.

QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 4 min
🤝 We Do · hinge & response

Which observation most strongly supports anaphase?

Everyone commits before explanation.

Use a button, point, say/sign or let an adult operate the chosen button. A retry is information, not a penalty.

QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 4 min
👩‍🏫 I Do 2 · connect / extend

Connect the model to the second idea

Connection: the model is useful when its visible pattern is translated into a scientific explanation.
Connection 1

Count each visible cell once in a defined field. Record the total number of cells and the number with defensible mitotic-stage evidence.

Connection 2

Calculate mitotic index = cells observed in mitosis ÷ total cells observed. For 10 mitotic cells among 50 total, the index is 0.20 or 20%.

Connection 3

Evaluate the result: section angle, overlapping cells, unclear stage boundaries and one small field can affect classification. Repeat fields and a consistent decision rule improve representativeness and repeatability.

MODEL STRENGTH

Use OBSERVATION → STAGE INFERENCE → REASON → LIMIT. For a count, show numerator, denominator and whether the answer is a fraction, decimal or percentage.

MODEL LIMIT

A micrograph is a two-dimensional snapshot of a three-dimensional, continuous process. Cell proportions can estimate relative stage occupancy only under assumptions and do not directly reveal the duration of an individual cell's stage.

QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 5 min
🤝 We Do 2 · scientific model / data

Observation, inference and uncertainty triage

Route each evidence card before building a stage sequence and calculating the sample's mitotic index.

Read the statement without adding hidden detail.Commit it to observation, stage/data inference or uncertainty.Repair any claim that exceeds the image or count.Freeze one sequence and one calculation only when evidence and inference are visibly separated.

Cards to place

Matching groups

The stage labels are present, but several have no visible evidence and the sample calculation is unstated.

🧩 Science glitch · find and repair it

Claim: Evidence glitch: the darkest cell must be in anaphase, and because most sampled cells are in interphase, this image proves interphase lasts exactly longest.

QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 12 min
✏️ Independent · evidence & transfer

Sequence and annotate cell-cycle images, calculate a simple mitotic index, and EVALUATE how confidently the sample supports each stage decision.

👐 Physical route

Teacher-approved micrographs or prepared slides, microscope if authorised, stage-evidence key, tally grid, calculator and command-word frame.

Same outcome: I can identify and sequence stages of the cell cycle from diagrams or micrographs, justify stage decisions with visible chromosome evidence, and evaluate uncertainty in snapshot data.

🖥 Offline digital / director route

Zoom and classify the same approved image set locally, then calculate the index and preserve uncertain classifications. Do not let automatic labels replace pupil evidence.

Same evidence: An ordered six-stage sequence, at least four observation-to-stage annotations, shown mitotic-index working and one justified limitation or improvement.

🧰 Equipment / setupTeacher-approved micrographs or prepared slides, microscope if authorised, stage-evidence key, tally grid, calculator and command-word frame.
🛡 Safety / sensoryUse prepared material only. Carry a microscope by arm and base, begin on low power, keep slides flat and report chipped glass. No pupil tissue sampling or unapproved online image upload is required.
🖥 Offline parityZoom and classify the same approved image set locally, then calculate the index and preserve uncertain classifications. Do not let automatic labels replace pupil evidence.
No-equipment/access route: Use enlarged high-contrast images, tactile chromosome overlays, partner description or eye-pointing with adult scribing. The same stage evidence, calculation and uncertainty judgement remain required.

◆ Supported

Match six clear images to named stages, underline one clue per image and calculate a mitotic index from a scaffolded tally.

Scaffold

Use: I can see __. This supports __ because __. Mitotic index = __ ÷ __.

▲ Standard

Classify mixed clear and ambiguous images, justify each decision, calculate the index and evaluate one sampling limitation.

Scaffold

Keep DESCRIBE, IDENTIFY, CALCULATE and EVALUATE responses separate.

★ Stretch

Create a defensible decision rule, compare two fields, calculate their indices and evaluate whether differences reflect biology, sampling or classification uncertainty.

Scaffold

Quantify the sample, preserve uncertain cases and avoid converting population proportions into exact stage duration.

Evidence gate

1 · Pupil decisionPrediction, question, method or choice is visible.
2 · Observable evidenceA result, source note, model state or adult observation is preserved.
3 · Pupil meaningAn ordered six-stage sequence, at least four observation-to-stage annotations, shown mitotic-index working and one justified limitation or improvement.
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

⏱ 4 min
🎫 Exit · receive and use the response

Finish with an edit or re-attempt on the existing work

Supported

Name the stage shown by chromosomes in one central line and give the visible clue.

Standard

Ten of 50 cells are visibly mitotic. Calculate the mitotic index and state one limitation.

Stretch

Evaluate the claim that the most common stage in one micrograph must be the exact longest stage for every cell.

Adult Audience

The familiar adult genuinely receives the pupil response, then says back the Science they heard or saw. The adult does not add a score or rewrite the pupil.

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

Session state is temporary. Reload clears responses; there is no account, upload or saved pupil identity.

⌂ Start
QUESTIONEVIDENCEPATTERNEXPLANATIONAPPLICATIONEVALUATION

LAUNCH rule: explanation is earned through prediction, observation, measurement, calculation or reasoning from evidence.

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

Staff route

TA Brief · Lesson overview

Priority

Settle, wait and protect the learning goal.

Least-prompt move

Use the least prompt needed, then fade it.

Prompt ladder

WAITSELF-PROMPTVISUAL CUEGENERAL VERBALSPECIFIC VERBALMODELDIRECT SUPPORT
Read-aloud availability: a familiar adult can read the exact current task while the text remains visible. Device speech is intentionally omitted so the deck asks for no media permission and stays dependable offline.

Guidance and access

Live Lundy loop

🛡 SPACE
🗣 VOICE
👂 AUDIENCE
⚙ INFLUENCE

SPACE available · VOICE waiting · AUDIENCE waiting · INFLUENCE waiting

Audience is real only when a familiar adult receives the response. Influence is real only when one next teaching move visibly changes.