I can calculate and graph relative amylase rates, judge what the evidence supports, and use enzyme and transport ideas in an exam-style explanation.
Success looks like
Show relative-rate working using 1 ÷ time with the unit s⁻¹.
Read or plot the pH–rate pattern and limit the conclusion to the evidence.
Link a method limitation to an improvement, then distinguish digestion from diffusion.
We will observe, work together, then use the evidence ourselves.
Arrival task
Arrival task
Choose a route. Think first, then check the answers together.
1. Time and rate
With the same starting starch and endpoint, which is faster: 90 s or 180 s?
Shorter time for the same measured change means faster breakdown.
Answer: 90 s is faster.
2. Read the endpoint
Blue-black means starch detected. Orange-brown means starch not detected. Which colour meets our endpoint?
Endpoint = first sampled time with starch not detected.
Answer: Orange-brown.
3. Show the working
Relative rate = 1 ÷ time. Use a calculator to find 1 ÷ 100.
Press 1 ÷ 100 =. Use time in seconds; rate unit is s⁻¹.
Answer: 1 ÷ 100 = 0.0100 s⁻¹ (0.01 s⁻¹ is also correct).
4. Match the instruction
DESCRIBE means state the pattern. EVALUATE means judge the evidence. Which asks for a strength and a limitation?
The command word tells you what the answer must do.
Answer: EVALUATE.
1. Time and rate
Explain why 90 s gives a larger relative rate than 180 s under matched conditions.
Relative rate = 1 ÷ time, for the same starting amount and endpoint.
Answer: The same measured change takes less time; 1/90 is larger than 1/180.
2. Read the endpoint
At 60 s starch is detected; at 90 s it is not. What endpoint value is used in the rate calculation?
Use the first observed endpoint, not an invented time between samples.
Answer: 90 s, while acknowledging the endpoint was reached after 60 s and by 90 s.
3. Show the working
Calculate relative rate for an endpoint of 120 s; show the equation, substitution and unit.
Relative rate = 1 ÷ time. A value to three significant figures is sufficient here.
Answer: Relative rate = 1/120 = 0.00833 s⁻¹.
4. Match the instruction
Distinguish DESCRIBE from EXPLAIN when answering about a graph.
Describe = state the pattern. Explain = link that pattern to scientific reasons.
Answer: Describe states how values change; explain uses biology, such as pH affecting the active site, to account for the pattern.
1. Time and rate
A trial takes twice as long to reach the same endpoint. What happens to its reciprocal relative rate?
Compare 1/t with 1/(2t). Starting amount and endpoint must be matched.
Answer: Its relative rate halves.
2. Read the endpoint
Why is 1/90 s⁻¹ an endpoint-based estimate rather than a direct instantaneous rate measurement?
The endpoint records one sampled stage of change; rate may vary during a reaction.
Answer: It summarises time to an observed endpoint, with sampling and colour limits. It does not continuously measure the amount changed per instant.
3. Show the working
For 120 s, compare 1/t with 1000/t. May the two values share one unlabelled graph axis?
The two conventions differ by a scale factor of 1000. This lesson uses 1/t only.
Answer: 1/120 = 0.00833 s⁻¹; 1000/120 = 8.33 on that stated scaled convention. They must not be mixed on one unlabelled axis.
4. Match the instruction
A graph has one result at each pH. Name one extra thing an EVALUATE answer needs beyond describing its peak.
Evaluate = use a strength or limitation to reach a supported judgement.
Answer: For example: one trial per pH limits repeatability evidence, so repeat matched trials before treating the peak as secure.
Starter
Starter · reverse the time
Matched amounts, same iodine endpoint: reaction A reaches the endpoint in 90 s; B takes 180 s. Which is faster?
Compare the rates.
Relative rate = 1 ÷ time, for matched starting amounts and endpoints. Unit: s⁻¹, read “per second”.
I do
I do · time becomes relative rate
Turn an endpoint into a relative rate
pH
Endpoint / s
6
120
1 · Identify the measured endpoint time: 120 s.
1/time is a comparative rate estimate, not grams of product per second.
1 ÷ 120 = 0.008333… s⁻¹, so 0.00833 s⁻¹ to 3 significant figures. Keep unrounded calculator values until the final answer. A no-endpoint result has no exact reciprocal to calculate.
We do
We do · build an evidence chain
Drag a card, or select it then choose its destination.
Choose a card, then a destination. You can change your mind.
Choose a card, place it, then explain the clue. Discuss one placement together before checking the rest.
I do
I do · read the graph honestly
Build the axes, then use the evidence
pH on x; relative rate / s⁻¹ on y. Equal numerical steps have equal spacing.
Five illustrative single runs, not mean rates. Points show what was sampled; do not claim an exact optimum between them.
We do
We do · repair and transfer
Draft explanation: “Enzymes are killed at pH 4. pH 7 is the exact optimum for every amylase, and diffusion breaks starch into sugar.”
Reference: enzymes are biological catalysts, not living organisms. Digestion breaks molecules down; diffusion is net movement from higher to lower concentration. pH can affect enzyme activity.
Which revision is supported?
In these single runs, rate rises from 0.00417 s⁻¹ at pH 4 to 0.0111 s⁻¹ at pH 7, then falls to 0.00667 s⁻¹ at pH 8. pH may affect the active site and catalysis. pH 7 is highest among those tested; repeats and more nearby pH values would help refine the inference. Amylase catalyses starch digestion; diffusion is a different process.
You do
You do · make the evidence answer
Use the supplied evidence. Write, draw, point, explain or direct an adult.
Open evidence and reference diagrams
Enzyme: biological catalyst; speeds a reaction without being used up. Substrate: substance it acts on. pH: a measure of acidity or alkalinity. Amylase acts on starch, producing smaller sugars.
pH
Endpoint / s
Relative rate / s⁻¹
4
240
0.00417
5
180
0.00556
6
120
0.00833
7
90
0.0111
8
150
0.00667
Supplied illustrative observations — not your practical results. Single runs; equal starting amounts and the same iodine endpoint. Samples every 30 s. pH 7: blue-black at 30/60 s, orange-brown at 90 s. Record 90 s.
Complete the reference graph: pH 4, 5 and 8 are shown; add pH 6 and pH 7. Stretch: add the separate repeat with a distinct symbol.
Rate: 1 ÷ endpoint time. At pH 7: 1 ÷ 90 = 0.0111 s⁻¹ (3 significant figures). These are single-run rates, not means. Highest among tested: pH 7; exact optimum is not established. The extra pH 7 repeat (120 s) is a separate trial, not silently averaged.
Topic 1 transfer: digestion breaks large molecules into smaller molecules. Diffusion is net particle movement from higher to lower concentration; it does not break a starch molecule apart. Enzymes are catalysts, not living organisms. pH changes can alter activity; slower timing alone does not prove permanent denaturation.
Describe = give a pattern; explain = link cause and effect; evaluate = use evidence and limits. An unobserved endpoint by 300 s establishes no exact reciprocal rate.
Supported
1. Use 1 ÷ time to calculate the pH 6 rate from 120 s and the pH 7 rate from 90 s.
Help with this question
Calculator steps: 1 ÷ 120 =; then 1 ÷ 90 =. Keep the unit s⁻¹.
2. Add pH 6 and pH 7 to the supplied rate graph. Match each pH to its calculated rate; the other three points are supplied.
Help with this question
Read pH along the bottom, then move up to the rate. Use the labelled example point.
3. Choose the highest rate in the first series. Complete “In these tested conditions, pH ___ was fastest because ___.”
Help with this question
Find the largest rate number, not the largest pH number. Include “in this series”.
4. The sampling interval is 30 s. Choose a limitation and a linked improvement: uncertain exact endpoint / use a shorter fixed interval if authorised.
Help with this question
Say “Because samples are separated by ___ s, we cannot know ___.”
5. The supplied diagram shows starch breaking into sugars, then particles moving from high to low concentration. Label the two changes: digestion / diffusion.
Help with this question
Digestion changes molecules chemically. Diffusion changes where particles are.
Standard
1. Calculate relative rate for pH 6 and pH 7, showing equation, substitution and units. Check that shorter time gives a larger value.
Help with this question
Write the formula first. We use 1/t throughout; no mixed 1000/t scale.
2. Complete the five-point graph using the two calculated rates and three supplied points. Label both axes and state the rise-and-fall pattern.
Help with this question
Use the supplied axes and three reference points; complete the two missing points without redrawing the whole graph.
3. Use one numerical comparison to identify the highest tested activity in the first series. Explain how pH can affect the enzyme’s active site.
Help with this question
Separate DESCRIBE (numbers/pattern) from EXPLAIN (active-site reasoning). Slower activity alone does not prove permanent denaturation.
4. Give one strength, one limitation and one linked improvement for the endpoint method. Use the separate pH 7 repeat of 120 s to qualify your confidence.
Help with this question
Use “A strength is …; a limit is …; therefore …”. Keep the 120 s repeat separate from the first series.
5. Exam-style transfer: distinguish enzyme digestion from diffusion in the supplied two-step diagram. Explain why movement from high to low concentration does not itself break starch into sugars.
Help with this question
Use the printed definitions. A catalyst speeds a reaction; a concentration gradient describes distribution.
Stretch
1. Calculate pH 6 and pH 7 relative rates. Compare the first pH 7 rate with its separate 120 s repeat, retaining both results.
Help with this question
The repeat is a second observation at pH 7. Do not average times or rates unless explicitly choosing and explaining that convention.
2. Complete the five-point first-series graph and place the separate repeat at the same pH 7 x-position with a distinct symbol. Explain why it is not pH 9 or a silently replaced point.
Help with this question
Same independent variable means the same x-position. Use a key for the repeat.
3. Evaluate “pH 7 is the exact optimum for every amylase”. Use the tested range, the repeat and the difference between data and a molecular explanation.
Help with this question
Highest first-series point is narrower than an exact universal optimum. Evaluate both precision and scope.
4. Give a strength–limitation–improvement chain. Explain which uncertainty a shorter authorised sampling interval reduces and which it leaves.
Help with this question
Target a named source of uncertainty; “repeat it” alone does not explain a smaller sampling gap.
5. Exam-style transfer: explain why “diffusion digests starch” confuses two processes. Use the supplied definitions, and state why an enzyme-rate graph alone cannot show how sugars cross a gut membrane.
Help with this question
Use what the graph measured to identify what it cannot establish. Do not infer a membrane mechanism from starch disappearance.
Exit
Exit ticket
Use your book OR one ticket. Show your explanation with the supplied evidence. Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Calculate the pH 6 relative rate, then choose the faster first-series result: pH 6 or pH 7.
Help with this question
Use 1 ÷ 120. For matched endpoints, shorter time means faster breakdown.
Answer guidance: 1/120 = 0.00833 s⁻¹; pH 7 is faster in the first series (90 s).
2. Choose the stronger conclusion: “pH 7 was fastest in this first series” or “pH 7 is best for every amylase”. Give one clue.
Help with this question
Consider what was tested and the separate repeat.
Answer guidance: The first statement is supported. Only pH 4–8 in these conditions were tested; the repeat also shows variation.
1. Calculate both first-series relative rates and use them for a bounded comparison.
Help with this question
Show 1 ÷ time and s⁻¹. End with “in this series”.
Answer guidance: pH 6: 0.00833 s⁻¹; pH 7: 0.0111 s⁻¹. pH 7 is faster in the first series under these matched conditions.
2. Use the repeat or sampling interval to give one limitation and a justified next investigation change.
Help with this question
Name the limitation before an improvement. A shorter interval must be authorised and feasible.
Answer guidance: Variation: repeat matched trials across all pH values to judge the pattern. Or 30 s timing gap: shorter fixed intervals narrow the endpoint window if authorised.
1. Does the pH 7 repeat strengthen the claim of an exact optimum? Use a rate and a comparison.
Help with this question
Its 120 s result is a separate observation at the same pH. Compare with pH 6.
Answer guidance: Repeat rate = 1/120 = 0.00833 s⁻¹, matching first-series pH 6. It shows variation and weakens an exact-optimum claim.
2. Give one targeted method improvement and explain why this graph still cannot prove permanent enzyme denaturation.
Help with this question
Distinguish better endpoint evidence from directly testing molecular change or recovery.
Answer guidance: A shorter authorised interval narrows the timing window, or repeats clarify variation. Lower activity alone does not establish irreversible structural change; the graph does not measure active-site structure or recovery.
A trial takes twice as long to reach the same endpoint. What happens to its reciprocal relative rate?
Answer guidance: Its relative rate halves.
2. Read the endpoint
Why is 1/90 s⁻¹ an endpoint-based estimate rather than a direct instantaneous rate measurement?
Answer guidance: It summarises time to an observed endpoint, with sampling and colour limits. It does not continuously measure the amount changed per instant.
3. Show the working
For 120 s, compare 1/t with 1000/t. May the two values share one unlabelled graph axis?
Answer guidance: 1/120 = 0.00833 s⁻¹; 1000/120 = 8.33 on that stated scaled convention. They must not be mixed on one unlabelled axis.
4. Match the instruction
A graph has one result at each pH. Name one extra thing an EVALUATE answer needs beyond describing its peak.
Answer guidance: For example: one trial per pH limits repeatability evidence, so repeat matched trials before treating the peak as secure.
Enzyme: biological catalyst; speeds a reaction without being used up. Substrate: substance it acts on. pH: a measure of acidity or alkalinity. Amylase acts on starch, producing smaller sugars.
pH
Endpoint / s
Relative rate / s⁻¹
4
240
0.00417
5
180
0.00556
6
120
0.00833
7
90
0.0111
8
150
0.00667
Supplied illustrative observations — not your practical results. Single runs; equal starting amounts and the same iodine endpoint. Samples every 30 s. pH 7: blue-black at 30/60 s, orange-brown at 90 s. Record 90 s.
Complete the reference graph: pH 4, 5 and 8 are shown; add pH 6 and pH 7. Stretch: add the separate repeat with a distinct symbol.
Rate: 1 ÷ endpoint time. At pH 7: 1 ÷ 90 = 0.0111 s⁻¹ (3 significant figures). These are single-run rates, not means. Highest among tested: pH 7; exact optimum is not established. The extra pH 7 repeat (120 s) is a separate trial, not silently averaged.
Topic 1 transfer: digestion breaks large molecules into smaller molecules. Diffusion is net particle movement from higher to lower concentration; it does not break a starch molecule apart. Enzymes are catalysts, not living organisms. pH changes can alter activity; slower timing alone does not prove permanent denaturation.
Describe = give a pattern; explain = link cause and effect; evaluate = use evidence and limits. An unobserved endpoint by 300 s establishes no exact reciprocal rate.
4. The sampling interval is 30 s. Choose a limitation and a linked improvement: uncertain exact endpoint / use a shorter fixed interval if authorised.
Help with this question
Say “Because samples are separated by ___ s, we cannot know ___.”
5. The supplied diagram shows starch breaking into sugars, then particles moving from high to low concentration. Label the two changes: digestion / diffusion.
Help with this question
Digestion changes molecules chemically. Diffusion changes where particles are.
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Calculate the pH 6 relative rate, then choose the faster first-series result: pH 6 or pH 7.
Help with this question
Use 1 ÷ 120. For matched endpoints, shorter time means faster breakdown.
2. Choose the stronger conclusion: “pH 7 was fastest in this first series” or “pH 7 is best for every amylase”. Give one clue.
Help with this question
Consider what was tested and the separate repeat.
LAUNCH · W8L3 · Supported · 4 minutes
Exit ticket
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Calculate the pH 6 relative rate, then choose the faster first-series result: pH 6 or pH 7.
Help with this question
Use 1 ÷ 120. For matched endpoints, shorter time means faster breakdown.
2. Choose the stronger conclusion: “pH 7 was fastest in this first series” or “pH 7 is best for every amylase”. Give one clue.
Help with this question
Consider what was tested and the separate repeat.
LAUNCH · GCSE Biology · Amylase Rate, Graph and Topic 1 Consolidation · Standard
Your task · 1 of 2
1. Calculate relative rate for pH 6 and pH 7, showing equation, substitution and units. Check that shorter time gives a larger value.
Help with this question
Write the formula first. We use 1/t throughout; no mixed 1000/t scale.
2. Complete the five-point graph using the two calculated rates and three supplied points. Label both axes and state the rise-and-fall pattern.
Help with this question
Use the supplied axes and three reference points; complete the two missing points without redrawing the whole graph.
3. Use one numerical comparison to identify the highest tested activity in the first series. Explain how pH can affect the enzyme’s active site.
Help with this question
Separate DESCRIBE (numbers/pattern) from EXPLAIN (active-site reasoning). Slower activity alone does not prove permanent denaturation.
LAUNCH · GCSE Biology · Amylase Rate, Graph and Topic 1 Consolidation · Standard
Your task · 2 of 2
4. Give one strength, one limitation and one linked improvement for the endpoint method. Use the separate pH 7 repeat of 120 s to qualify your confidence.
Help with this question
Use “A strength is …; a limit is …; therefore …”. Keep the 120 s repeat separate from the first series.
5. Exam-style transfer: distinguish enzyme digestion from diffusion in the supplied two-step diagram. Explain why movement from high to low concentration does not itself break starch into sugars.
Help with this question
Use the printed definitions. A catalyst speeds a reaction; a concentration gradient describes distribution.
LAUNCH · GCSE Biology · Amylase Rate, Graph and Topic 1 Consolidation · Standard
LAUNCH · W8L3 · Standard · 4 minutes
Exit ticket
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Calculate both first-series relative rates and use them for a bounded comparison.
Help with this question
Show 1 ÷ time and s⁻¹. End with “in this series”.
2. Use the repeat or sampling interval to give one limitation and a justified next investigation change.
Help with this question
Name the limitation before an improvement. A shorter interval must be authorised and feasible.
LAUNCH · W8L3 · Standard · 4 minutes
Exit ticket
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Calculate both first-series relative rates and use them for a bounded comparison.
Help with this question
Show 1 ÷ time and s⁻¹. End with “in this series”.
2. Use the repeat or sampling interval to give one limitation and a justified next investigation change.
Help with this question
Name the limitation before an improvement. A shorter interval must be authorised and feasible.
1. Calculate pH 6 and pH 7 relative rates. Compare the first pH 7 rate with its separate 120 s repeat, retaining both results.
Help with this question
The repeat is a second observation at pH 7. Do not average times or rates unless explicitly choosing and explaining that convention.
2. Complete the five-point first-series graph and place the separate repeat at the same pH 7 x-position with a distinct symbol. Explain why it is not pH 9 or a silently replaced point.
Help with this question
Same independent variable means the same x-position. Use a key for the repeat.
3. Evaluate “pH 7 is the exact optimum for every amylase”. Use the tested range, the repeat and the difference between data and a molecular explanation.
Help with this question
Highest first-series point is narrower than an exact universal optimum. Evaluate both precision and scope.
4. Give a strength–limitation–improvement chain. Explain which uncertainty a shorter authorised sampling interval reduces and which it leaves.
Help with this question
Target a named source of uncertainty; “repeat it” alone does not explain a smaller sampling gap.
5. Exam-style transfer: explain why “diffusion digests starch” confuses two processes. Use the supplied definitions, and state why an enzyme-rate graph alone cannot show how sugars cross a gut membrane.
Help with this question
Use what the graph measured to identify what it cannot establish. Do not infer a membrane mechanism from starch disappearance.
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Does the pH 7 repeat strengthen the claim of an exact optimum? Use a rate and a comparison.
Help with this question
Its 120 s result is a separate observation at the same pH. Compare with pH 6.
2. Give one targeted method improvement and explain why this graph still cannot prove permanent enzyme denaturation.
Help with this question
Distinguish better endpoint evidence from directly testing molecular change or recovery.
LAUNCH · W8L3 · Stretch · 4 minutes
Exit ticket
Say it, write it, draw it, sign it, choose it or show it; an adult can scribe it.
Illustrative matched-condition data: pH 6 endpoint 120 s; pH 7 endpoint 90 s. A separate pH 7 repeat gave 120 s. Relative rate = 1 ÷ time in seconds (s⁻¹). Samples were 30 s apart; pH 4–8 were tested.
1. Does the pH 7 repeat strengthen the claim of an exact optimum? Use a rate and a comparison.
Help with this question
Its 120 s result is a separate observation at the same pH. Compare with pH 6.
2. Give one targeted method improvement and explain why this graph still cannot prove permanent enzyme denaturation.
Help with this question
Distinguish better endpoint evidence from directly testing molecular change or recovery.
Teacher answers · W8L3
Shared activities
Starter · reverse the time: 90 s is faster than 180 s for matched amounts and the same endpoint. 1/90 ≈ 0.0111 s⁻¹; 1/180 ≈ 0.00556 s⁻¹. Doubling the time halves the relative rate. Worked rate and graph point: Relative rate = 1/time = 1/120 = 0.00833 s⁻¹. Plot pH 6 at 0.00833 s⁻¹; pH has no unit. Build an evidence chain: Calculation checks: a reciprocal value; shorter time gives larger rate. Pattern/conclusion: pH 7 has the highest first-series rate among tested values; rate rises to pH 7 then falls at pH 8. Evaluation: colour judgement, shorter sampling intervals, and transparent treatment of repeats/anomalies. Graph and claim repair: First-series rates are 0.00417, 0.00556, 0.00833, 0.0111 and 0.00667 s⁻¹ for pH 4–8. The separate pH 7 repeat is 0.00833 s⁻¹, plotted with a distinct symbol at x = 7. These values do not prove an exact universal optimum or permanent denaturation. Topic 1 process labels: Starch chemically breaking into smaller sugars is enzyme digestion. Net movement of particles from higher to lower concentration is diffusion. Movement does not itself chemically break starch into sugars.
Supported arrival
1. 90 s is faster.
2. Orange-brown.
3. 1 ÷ 100 = 0.0100 s⁻¹ (0.01 s⁻¹ is also correct).
2. Plot (6, 0.00833) and (7, 0.0111), pH on x-axis, relative rate/s⁻¹ on y-axis. Accept equivalent pupil-directed placement.
3. pH 7 is fastest in the first series, because 0.0111 s⁻¹ is the highest measured relative rate (or 90 s the shortest time).
4. The exact endpoint between samples is unknown. A shorter fixed interval could narrow the timing window if authorised and feasible; it does not remove every uncertainty.
5. Starch breaking into smaller sugars: digestion. Particles moving down a concentration gradient: diffusion.
Supported exit
1. 1/120 = 0.00833 s⁻¹; pH 7 is faster in the first series (90 s).
2. The first statement is supported. Only pH 4–8 in these conditions were tested; the repeat also shows variation.
Standard arrival
1. The same measured change takes less time; 1/90 is larger than 1/180.
2. 90 s, while acknowledging the endpoint was reached after 60 s and by 90 s.
3. Relative rate = 1/120 = 0.00833 s⁻¹.
4. Describe states how values change; explain uses biology, such as pH affecting the active site, to account for the pattern.
Standard independent task
1. Relative rate = 1/time. pH 6: 1/120 = 0.00833 s⁻¹. pH 7: 1/90 = 0.0111 s⁻¹. The shorter time produces the larger reciprocal rate.
2. x-axis pH (no unit); y-axis relative rate/s⁻¹. Points 4:0.00417, 5:0.00556, 6:0.00833, 7:0.0111, 8:0.00667. Rate rises from pH 4 to 7, then falls at pH 8.
3. pH 7 has the highest first-series rate, 0.0111 s⁻¹ versus e.g. pH 4 at 0.00417 s⁻¹. pH can alter the active-site environment/shape and affect substrate binding and catalysis. The graph does not prove permanent denaturation or an exact universal optimum.
4. Strength: matched starting amounts/temperature and a common endpoint support comparison. Limitation: 30 s intervals or subjective colour judgement. Improvement: shorter fixed intervals if authorised, or consistent agreed colour judgement; link it to the limitation. The pH 7 repeat gives 120 s, so variation weakens confidence from one series.
5. Digestion is chemical breakdown catalysed by enzymes; amylase breaks starch into smaller sugars. Diffusion is net particle movement from higher to lower concentration. Moving particles does not itself change starch molecules chemically.
Standard exit
1. pH 6: 0.00833 s⁻¹; pH 7: 0.0111 s⁻¹. pH 7 is faster in the first series under these matched conditions.
2. Variation: repeat matched trials across all pH values to judge the pattern. Or 30 s timing gap: shorter fixed intervals narrow the endpoint window if authorised.
Stretch arrival
1. Its relative rate halves.
2. It summarises time to an observed endpoint, with sampling and colour limits. It does not continuously measure the amount changed per instant.
3. 1/120 = 0.00833 s⁻¹; 1000/120 = 8.33 on that stated scaled convention. They must not be mixed on one unlabelled axis.
4. For example: one trial per pH limits repeatability evidence, so repeat matched trials before treating the peak as secure.
Stretch independent task
1. pH 6 = 1/120 = 0.00833 s⁻¹. First pH 7 = 1/90 = 0.0111 s⁻¹. Separate repeat pH 7 = 1/120 = 0.00833 s⁻¹; it equals the first pH 6 rate. Keep both pH 7 observations visible.
2. First-series graph uses the five supplied/calculated coordinates. Repeat belongs at (7, 0.00833), as the same IV condition measured again, with its own symbol/key. Do not silently replace or average raw points.
3. The claim is too broad. pH 7 is highest only in the first series among pH 4–8 tested. A 120 s repeat shows variation and matches the first pH 6 time. Untested values and other amylase sources/conditions remain unknown. pH effects on active sites are a biological explanation, not direct molecular observations from this graph.
4. Matched starting amounts/temperature and common endpoint strengthen validity. A 30 s interval limits timing precision; a shorter fixed interval could narrow that gap if feasible/authorised. It does not remove subjective colour judgement, variable starting conditions or all repeat variation.
5. Digestion chemically breaks large molecules down; diffusion moves particles down a concentration gradient. They are different processes. The graph measures an endpoint in starch breakdown, not membrane transport, concentration gradients across a gut wall or transport proteins.
Stretch exit
1. Repeat rate = 1/120 = 0.00833 s⁻¹, matching first-series pH 6. It shows variation and weakens an exact-optimum claim.
2. A shorter authorised interval narrows the timing window, or repeats clarify variation. Lower activity alone does not establish irreversible structural change; the graph does not measure active-site structure or recovery.
Lead with VF in the practical and exit tasks. Written feedback is for extended writing only, strategic and not every piece (Curriculum Policy 2026/27 §14.3).
Core practical evidence. The Edexcel core practical is evidenced by the pupil doing the practical. The illustrative route evidences the interpretation skills only, and is never recorded as core practical completion.
Code
Meaning
VF
Verbal feedback given here
WS
Worked with support
I
Independent
NS + …
Next step one specific thing
E
Evidence captured on the school’s digital evidence platform
R
Responded loop closed (Audience has happened)
//
Self-edit point
?
Read this back to me
Curriculum Policy 2026/27 §14.3 summary: VF WS I NS E R (six codes; NS “next step”, E “evidence on digital software app”, R “responded to feedback”). The Feedback Policy, the code source, adds // and ? and expands NS to one specific thing and R to loop closed.
Voice + Audience = R: the pupil responds AND the adult genuinely engages with that response; add R only when both have happened. For a margin edit, the policy says: “in the same colour, on the same page”.
One NS + next step: choose the relevant prompt
Supported: Repair one rate calculation using 1 ÷ time, then check that the shorter time gives the larger rate.
Standard: Add a number and “among the values tested” to one graph conclusion; keep the explanation separate from the observation.
Stretch: Use the separate repeat to limit your optimum claim, then link one method improvement to the uncertainty it actually reduces.
Read the cause, then choose the teaching move
Secure: Use the same evidence-versus-claim discipline in the next taught science week, w/c 2 November.
Mixed: Re-work one time-to-rate example and connect it to a single graph point.
Misconception: Contrast a larger time with its smaller reciprocal and separate a tested peak from a universal optimum.
Access barrier: Use pre-scaled axes, a calculator key sequence and pupil-directed point placement.
Method-or-data problem: Keep original and repeat results distinct; re-establish matched amounts, endpoint rule and time units before interpreting.
Named involvement opportunity
We do · build an evidence chain. Invite a pupil to classify a rate calculation, graph claim or evaluation statement and justify its role; give feedback on the reason. VF records verbal feedback actually given.
Spoken arrival guidance · say once
In our amylase investigation lesson, your evidence showed ___, so today we're starting with ___.
LAUNCH: “Adult engages with the edit against the mark scheme / model answer before R.” The pupil owns the response; no adult counter-initial or extra receipt. Codes stay in books. No second next step or retrospective closure.
LAUNCH SCIENCE · W8 · w/c 19 October 2026
First lesson back
Staff copy — not for pupil books
Before the lesson · scan the books for five minutes
Notice which codes appear, any unclosed NS +, and whether pupil responses are present. The policy allows an edit in the same colour, on the same page.
Existing NS + is history
Read a next step set during the absence for information. Do not chase it, back-mark it or retrospectively close it. Begin fresh feedback from W8L1; never recreate a missed close.
Ask the cover teacher and TAs
What was actually taught? Who was in the room? What changed for any individual pupil?
Check the roll
Compare the current register with the names in the books. New arrivals have no prior evidence; that is not a deficit. Everyone meets the same lesson from the same page.
Arrival read-off · decide by about minute eight
Use the four arrival questions, with the help used in view. An absent response is information about access and starting point, not a pupil label. Choose ONE adjustment for that pupil within the existing lesson time.
1 · Catalyst and substrate
Secure: separates the reusable catalyst from the changing substrate. Partial: gives one role. Absent: no usable distinction yet. Secure → use the stretch mechanism prompt. Partial → hold the product-release model longer. Absent → point to the unchanged enzyme and use the supported stem.
2 · Substrate or valid comparison
Secure: identifies starch or rejects two changed factors with a reason. Partial: identifies one factor only. Absent: no link to the supplied fact. Secure → ask for the competing cause. Partial → re-read the local clue. Absent → use the supported model labels during We do.
3 · Controls or repeats
Secure: links matching conditions or repeats to evidence quality. Partial: says “fair” or “accurate” without why. Absent: no usable reason yet. Secure → offer the stretch control question. Partial → hold the controlled-comparison example. Absent → complete the supported “keep the same because” prompt together.
4 · Changed factor and endpoint
Secure: separates pH from measured time, or explains a shared stopping rule. Partial: names one only. Absent: confuses cause and measure. Secure → use the timing-precision extension. Partial → point to the change/measure headings. Absent → contrast the two labelled iodine samples in the existing model.
Choose a route at each task using what the pupil shows. Switching adds no task, record or label.
After W8L3 · one read, once
Use the rates and explanation evidence to shape the plan for w/c 2 November, after half term. The book response or one exit ticket is enough; no report or form.