LF-15 · TEACHER LESSON PLAN

Catalase enzyme lab

Test how reaction temperature changes the evidence from potato catalase

BiologyGrades 8–1030–40 minHazard medium; 3% hydrogen peroxide irritates eyes and skinNGSS MS-PS1-2

01 //

Driving question

START THE LESSON WITH THISHow does the starting reaction temperature relate to catalase evidence in nine fresh potato trials?

02 //

Learning objectives

Students compare cold, room-temperature and comfortably warm reactions with three independent fresh trials per temperature.
Students measure starting temperature, seconds to first clear bubbles and foam height after exactly 60 seconds; then compare means and ranges.
Students explain how catalase activity can change with temperature and why foam height is an indirect indicator.

03 //

Standards

Dimension	Alignment
Performance expectation	MS-PS1-2Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. (Partial alignment: students observe oxygen bubbles and foam while hydrogen peroxide reacts with potato catalase, but they do not systematically compare a full set of reactant and product properties.)
Practices	SEP 3Plan and carry out investigations. SEP 4Analyze and interpret data.
Core idea	PS1.BIn a chemical reaction, atoms are rearranged to form new substances; the number and kinds of atoms are conserved.
Crosscutting	Stability and changeExplanations of stability and change in natural or designed systems can be constructed by examining the changes over time.

Standard text paraphrased from the Next Generation Science Standards. Alignment is partial: this activity measures reaction proxies rather than identifying all before-and-after substance properties.

03A //

State standards crosswalk

Use the row as a planning crosswalk, then confirm local district pacing and grade placement. “Partial” labels describe a skill connection, not full mastery of the complete standard.

State	Verified standard	How this lesson aligns	Official source
California	CA NGSS MS-PS1-2	Partial connection: gas bubbles and foam are observations of a reaction, but students do not compare all relevant substance properties before and after interaction.	Open standard ↗
Texas	Science.7.6(C)	Partial connection: students use gas production as evidence while distinguishing a chemical reaction from a physical change; they do not survey other kinds of matter changes.	Open standard ↗
Florida	SC.8.P.9.2	Partial connection: students observe a chemical change indicator in one enzyme reaction, but do not compare a broad range of physical and chemical changes.	Open standard ↗
New York	NYSSLS MS-PS1-2	Partial connection: students interpret bubbling and foam as evidence, but do not analyze a systematic set of substance properties before and after the reaction.	Open standard ↗
Pennsylvania	STEELS 3.2.6-8.D	Partial connection: students record visible gas and foam evidence, but do not test multiple properties of both substances before and after interaction.	Open standard ↗

04 //

Materials and prep timeline

PER GROUP

Nine equal-thickness potato disks from one potato; one fresh disk per independent trial
3% household hydrogen peroxide: nine 15 mL portions (135 mL total)
Nine identical clear, open reaction containers and a tray
Three water-bath cups for cold (about 5–10 °C), measured room temperature, and comfortably warm (about 35–40 °C); thermometer
Graduated cylinder, ruler, stopwatch, labels, goggles and recording sheet

TEACHER ONLY

Adult cuts nine equal-diameter, equal-thickness disks and prepares the three baths. Keep the warm bath at or below 40 °C; do not use boiling water or flames.
Provide splash goggles and only 3% household hydrogen peroxide. Measure nine fresh 15 mL portions, one per reaction.
Let each dry disk and its peroxide portion equilibrate in the same bath for about five minutes before combining. Record actual starting temperature.
Set the open reactions on a tray; keep containers open so oxygen can escape. Provide the product-label/school rinse procedure and handwashing.

CLASS-SIZE KIT PLANNER

One per-group kit contains every item in the team materials list above. Groups are balanced around the listed 3–4 students target.

Students	Groups	Per-group kits	Student sheets	Suggested group split
20	6	6 complete kits	20 copies	2 groups of 4 and 4 groups of 3
25	7	7 complete kits	25 copies	4 groups of 4 and 3 groups of 3
30	8	8 complete kits	30 copies	6 groups of 4 and 2 groups of 3

0–5 MINPredict and prepare

Predict how starting reaction temperature may affect bubble-start time. Review goggles, no flame, no tasting and open reaction vessels.

5–12 MINSet up nine trials

Label three reaction cups per temperature. Measure 15 mL peroxide per cup and use nine fresh matched disks. Equilibrate peroxide and dry disks in the same bath for about five minutes.

12–27 MINRun the repeated reactions

For each condition, combine one disk and one peroxide portion, time to first clear bubbles for up to 60 seconds, and record all three independent trials. If none appear by 60 seconds, record that limit rather than assigning a time. Measure actual starting temperature.

27–35 MINMeasure foam and summarize

At exactly 60 seconds, measure foam height in mm. For each temperature, retain the three readings and compare the mean and range for both measures.

35–40 MINInterpret and clean

Compare results without assuming a universal order or optimum. Foam depends on bubble stability as well as gas production; follow teacher cleanup directions.

04A //

Lab figures and data visuals

Reviewed article images support the lesson flow. Use the tables and student sheet to record actual observations; pictured patterns are not target results.

Open potato-catalase cups represent cold, room-temperature and comfortably warm reactions beside goggles and a timer. — **Control the starting reaction temperature.**Equilibrate each matched potato disk and peroxide portion in the same bath, then compare three independent trials at a defined endpoint.

A holographic catalase mechanism shows hydrogen peroxide breaking down into water and oxygen bubbles. — **Catalase releases oxygen from peroxide.**Catalase speeds the balanced reaction 2 H₂O₂ → 2 H₂O + O₂; the observed bubbles are oxygen, while foam remains an indirect measure.

A blank comparison chart records bubble-start time and 60-second foam height for cold, room and warm reaction temperatures without fabricated results. — **Measure before drawing a conclusion.**Plot the mean of three independent trials and keep individual values visible; high heat can alter enzyme shape and reduce activity.

04B //

Printable shopping list

TEACHER PREP · Catalase enzyme lab

Shopping and staging checklist

Multiply the per-group kit contents by the class-size planner. The teacher section includes teacher-provided materials and setup or safety notes.

PER-GROUP KITS

Nine equal-thickness potato disks from one potato; one fresh disk per independent trial
3% household hydrogen peroxide: nine 15 mL portions (135 mL total)
Nine identical clear, open reaction containers and a tray
Three water-bath cups for cold (about 5–10 °C), measured room temperature, and comfortably warm (about 35–40 °C); thermometer
Graduated cylinder, ruler, stopwatch, labels, goggles and recording sheet

TEACHER-PROVIDED MATERIALS + SETUP RULES

Adult cuts nine equal-diameter, equal-thickness disks and prepares the three baths. Keep the warm bath at or below 40 °C; do not use boiling water or flames.
Provide splash goggles and only 3% household hydrogen peroxide. Measure nine fresh 15 mL portions, one per reaction.
Let each dry disk and its peroxide portion equilibrate in the same bath for about five minutes before combining. Record actual starting temperature.
Set the open reactions on a tray; keep containers open so oxygen can escape. Provide the product-label/school rinse procedure and handwashing.

QUANTITIES BY CLASS SIZE

Material	Per group kit	20 students	25 students	30 students
Medium potatoes for fresh disks	1	6	7	8
3% household hydrogen peroxide	135 mL	810 mL	945 mL	1,080 mL
Clear open reaction containers	9	54	63	72
Water-bath cups	3	18	21	24
Water-bath cups	3	18	21	24
Tray, graduated cylinder, ruler, timer and thermometer	1 of each	6 of each	7 of each	8 of each
Safety goggles	1 per student	20	25	30
Student recording sheets	1 per student	20	25	30

Prepare 6 kits for 20 · 7 kits for 25 · 8 kits for 30 students.

05 //

Lesson flow

Minutes	What happens
0–5 min	Engage Predict how starting reaction temperature may affect bubble-start time. Review goggles, no flame, no tasting and open reaction vessels.
5–12 min	Explore Set up three independent cups per temperature with fresh matched disks and 15 mL of peroxide each. Equilibrate both reactants in the same bath.
12–27 min	Explore Run all nine reactions; time from contact to first clear bubbles for up to 60 seconds and record actual starting temperature. If none appear, record not observed by 60 seconds.
27–35 min	Explain At exactly 60 seconds, measure foam height in mm. Compare all three readings, then calculate each condition's mean and range.
35–40 min	Evaluate Interpret the measured pattern without claiming a universal optimum. Foam depends on bubble stability as well as gas production.

06 //

Discussion questions

1. What do the first bubbles show in this potato test?

SAMPLE ANSWERThey are oxygen gas produced as catalase in potato tissue speeds hydrogen peroxide breakdown; they are evidence of reaction, not a direct count of enzyme molecules.

2. Why could a warm disk bubble sooner than a cold disk?

SAMPLE ANSWERIn a moderate range, warming can increase molecular motion and reaction rate. The class should compare its timed readings; excessively high heat can change catalase's shape.

3. Why might the tallest foam not identify the fastest reaction by itself?

SAMPLE ANSWERFoam height also depends on bubble size and stability. The 60-second height is an indirect indicator, so compare it with time to first bubbles.

4. Why repeat each temperature three times?

SAMPLE ANSWERFresh independent trials show variation between potato disks. Keep all three values and compare mean and range rather than relying on one result.

5. What limits the conclusion from three temperature conditions?

SAMPLE ANSWERThey do not locate an exact temperature optimum. The measured range, potato tissue, starting temperatures and foam behavior all limit the conclusion.

07 //

Common misconceptions

STUDENTS OFTEN SAY“The potato is making air bubbles.”

BETTER IDEACatalase speeds the breakdown of hydrogen peroxide and releases oxygen gas; the bubbles are that gas.

STUDENTS OFTEN SAY“The warmest sample must always react fastest.”

BETTER IDEAModerate warming may increase activity, but too much heat can alter the enzyme. Test the stated temperatures rather than assuming a universal maximum.

STUDENTS OFTEN SAY“Foam height is the amount of oxygen.”

BETTER IDEAFoam is an indirect measure affected by bubble stability and liquid properties; use the fixed 60-second endpoint and also record bubble-start time.

08 //

Differentiation

SUPPORT

Use labeled cold, room and warm cups and a visual start/stop timing card.
Provide a millimeter ruler and demonstrate measuring from liquid surface to top of foam without touching it.
Offer: ‘The __ disk began bubbling in __ s and had __ mm of foam at 60 s.’

EXTEND

Repeat each condition with fresh disks and fresh 15 mL peroxide portions; compare ranges, not only single readings.
Measure bath temperatures and plot bubble-start time against measured temperature.
Design a follow-up with another moderate temperature while holding disk dimensions and peroxide constant; do not use boiling samples.

09 //

Assessment rubric

Criterion	Beginning	Developing	Secure
Fair comparison	Changes several conditions or reuses a reacted disk.	Matches some conditions but omits one control such as disk size or peroxide volume.	Uses fresh matched disks, equal peroxide volumes and open identical containers across temperatures.
Observations	Leaves bubble time or foam height blank.	Records observations but omits units or the 60-second endpoint.	Records time to first bubbles in seconds and foam height in millimeters at 60 seconds.
Evidence and reasoning	Makes a claim without citing measurements.	Uses one measure but treats foam as direct oxygen volume.	Uses both measured indicators and explains catalase and temperature with the limits of foam height.
Safe practice	Touches peroxide or seals a bubbling vessel.	Uses goggles but needs reminders about open vessels or cleanup.	Wears goggles, uses only 3% peroxide with adult supervision, keeps vessels open and follows rinse/cleanup directions.

10 //

Vocabulary

Catalase – An enzyme in potato tissue that speeds hydrogen peroxide breakdown.
Enzyme – A molecule that speeds a chemical reaction without being used up in one reaction.
Substrate – The substance an enzyme acts on; here, hydrogen peroxide.

Denature – To change a protein's shape so it no longer works in the same way.
Reaction rate – How quickly a reaction proceeds, measured here by bubble-start time and foam at a fixed time.
Oxygen – A gas released as catalase breaks hydrogen peroxide into water and oxygen.

11 //

Safety, cleanup and troubleshooting

BEFORE STUDENTS TOUCH ANYTHING

Hydrogen peroxide can irritate skin and eyes at higher concentrations — wear goggles and avoid contact with skin.
Wear splash goggles and use adult supervision with 3% household hydrogen peroxide only. Never use concentrated peroxide; keep it off skin and out of eyes and mouths.
Keep the reaction vessel open and on a tray. If solution splashes, stop and follow the product label and the classroom rinse procedure.
Use fresh potato disks for each trial — a disk that has already reacted has used up some of its catalase.
Do not seal the container while it's bubbling — the reaction releases oxygen gas that needs to escape.

Troubleshooting: If bubbling is hard to see, use the same clear container and lighting and record the observation as unclear rather than guessing. Use a fresh disk for every repeat. If a splash occurs, stop and follow the product label and classroom rinse procedure; never cap a reacting container.