LF-03 · TEACHER LESSON PLAN

Elephant toothpaste

How a catalyst speeds up hydrogen peroxide breaking down

ChemistryGrades 5–845 minHazard medium; warm overflow and 3% hydrogen peroxideNGSS MS-PS1-2

01 //

Driving question

START THE LESSON WITH THISHow does the amount of yeast added change how fast and how high the foam rises?

02 //

Learning objectives

Students plan a fair comparison using 1, 2 and 3 teaspoons of yeast while keeping the 3% hydrogen peroxide, soap, bottle and yeast-water temperature consistent.
Students measure three fresh trials at each of 1, 2 and 3 teaspoons of yeast, then compare mean peak height, range and mean plateau time.
Students interpret whether the foam and bottle warming are evidence of a chemical reaction, while distinguishing evidence from a complete analysis of substance properties.

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 foam and heat as evidence of a reaction; the assessment boundary lists density, melting point, boiling point, solubility, flammability and odor as the properties analyzed.)
Practices	SEP 3Plan and carry out investigations.
Core idea	PS1.BIn a chemical process, the atoms that make up the original substances are regrouped into different molecules, and these new substances have different properties from those of the reactants.
Crosscutting	PatternsMacroscopic patterns are related to the nature of microscopic and atomic-level structure.

Standards text paraphrased from nextgenscience.org. Alignment is partial; this hands-on activity does not cover every part of the performance expectation.

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	Analyze evidence that substances interacted; partial because foam and warmth support a reaction explanation but do not test the full listed property set.	Open standard ↗
Texas	SCIENCE.8.1.F	Organize repeated observations and use means to find patterns; supports comparing maximum foam height and plateau time.	Open standard ↗
Florida	SC.8.N.1.1	Plan investigations, identify variables, collect and interpret data, and defend conclusions; strong investigation alignment.	Open standard ↗
New York	MS-PS1-2	Analyze before-and-after substance properties for reaction evidence; partial because foam and warmth alone do not assess every property in the boundary.	Open standard ↗
Pennsylvania	3.2.6-8.D	Analyze properties before and after substances interact; partial because the foam-height investigation is evidence-focused, not a full diagnostic property comparison.	Open standard ↗

04 //

Materials and prep timeline

PER GROUP

1.08 L of teacher-portioned 3% household hydrogen peroxide for nine runs
Active dry yeast: three 1-tsp, three 2-tsp and three 3-tsp portions
540 mL dish soap and 540 mL warm water, portioned to match each run
One 600 mL bottle, rinsed and fully dried between runs; separate yeast cups
Ruler, timer, labels, tray, goggles and cleanup towels

TEACHER ONLY

Use only 3% household hydrogen peroxide; do not substitute stronger lab or salon peroxide. Keep the peroxide amount and bottle setup the same across trials.
Set the bottle on a tray. Check goggles, supervise the warm foam and keep the bottle open; never seal it.
Provide fresh measured ingredients for each run. Rinse and fully dry the bottle between trials; direct students not to taste or touch the foam and arrange 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	5	5 complete kits	20 copies	4 students per group
25	7	7 complete kits	25 copies	4 or 3 students per group
30	8	8 complete kits	30 copies	4 or 3 students per group

0–6 MINPredict and review

Read the driving question, predict how yeast amount may affect height and speed, and review goggles, tray, open-bottle setup and the 3% peroxide-only rule.

6–12 MINSet up nine matched runs

Label three trials each for 1, 2 and 3 teaspoons of yeast. Measure equal peroxide, soap and 60 mL warm water for every run; keep water temperature and the bottle matched.

12–30 MINReact and measure

Run all nine fresh trials one at a time. Record height every 10 seconds until it is unchanged or lower at two consecutive checks. Rinse and fully dry the open bottle between runs.

30–38 MINCompare the repeated data

Calculate each yeast condition's mean peak height, range and mean plateau time. Graph the mean height and discuss variation instead of treating one unusually foamy run as the result.

38–45 MINExplain and clean

Use the repeated measurements, foam and warmth as evidence of a chemical reaction, then name one limit of that evidence. Let the adult direct cleanup and wash hands.

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.

The open 3% hydrogen-peroxide classroom reaction uses yeast and soap in a catch tray, with goggles and a reminder to keep the bottle open. — **Use the dilute classroom setup.**Wear goggles, work over a tray, and keep the reaction bottle open to the air.

Catalase speeds hydrogen peroxide breakdown into water and oxygen, whose bubbles are trapped by soap to form foam. — **Connect catalase with oxygen foam.**Catalase speeds the reaction; soap traps oxygen bubbles, while the enzyme is not used up.

Three open bottles compare one, two and three teaspoons of yeast while peroxide, soap, bottle size and yeast-water temperature stay the same. — **Change yeast amount only.**Record the chosen foam-height or rise-time endpoint for every trial; foam height is a proxy, not a direct oxygen-volume measure.

04B //

Printable shopping list

TEACHER PREP · Elephant toothpaste

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

1.08 L of teacher-portioned 3% household hydrogen peroxide for nine runs
Active dry yeast: three 1-tsp, three 2-tsp and three 3-tsp portions
540 mL dish soap and 540 mL warm water, portioned to match each run
One 600 mL bottle, rinsed and fully dried between runs; separate yeast cups
Ruler, timer, labels, tray, goggles and cleanup towels

TEACHER-PROVIDED MATERIALS + SETUP RULES

Use only 3% household hydrogen peroxide; do not substitute stronger lab or salon peroxide. Keep the peroxide amount and bottle setup the same across trials.
Set the bottle on a tray. Check goggles, supervise the warm foam and keep the bottle open; never seal it.
Provide fresh measured ingredients for each run. Rinse and fully dry the bottle between trials; direct students not to taste or touch the foam and arrange handwashing.

Prepare 5 kits for 20 · 7 kits for 25 · 8 kits for 30 students.

05 //

Lesson flow

Minutes	What happens
0–6	Engage Ask how yeast amount may affect foam height and speed. Record a prediction and review goggles, tray, open bottle and use of 3% household peroxide only.
6–12	Explore Label three trials each for 1, 2 and 3 teaspoons. Match peroxide, soap, bottle size and 60 mL warm water at the same temperature for every run.
12–30	Explore Run all nine trials. Record height at 10-second intervals until it is unchanged or lower at two checks in a row; rinse and fully dry the open bottle between runs.
30–38	Explain Compare mean peak heights, ranges and mean plateau times. Explain that extra yeast can speed the reaction while fixed peroxide limits total product.
38–45	Evaluate Use repeated data, foam and warmth as reaction evidence and identify what these observations alone cannot establish. Have the adult direct cleanup; wash hands.

06 //

Discussion questions

1. Why measure both foam height and time to plateau?

SAMPLE ANSWERHeight describes the maximum foam column while time describes how quickly it develops. The two measurements can show different effects of changing yeast amount.

2. Why might 3 teaspoons not make a taller column than 2 teaspoons?

SAMPLE ANSWERHydrogen peroxide is a reactant. Once the available peroxide is used, adding more catalyst may not increase the total oxygen produced or the foam height.

3. What do foam and warmth suggest?

SAMPLE ANSWERGas bubbles and released heat are evidence that substances changed. These observations support a reaction explanation but do not analyze every property named in the performance expectation.

4. Why keep the peroxide concentration and bottle size the same?

SAMPLE ANSWERThose conditions affect how much gas can form and how high foam rises. Matching them helps isolate yeast amount as the planned difference.

07 //

Common misconceptions

STUDENTS OFTEN SAY“The foam is toothpaste, so it is safe to touch or taste.”

BETTER IDEAThe foam is not toothpaste or food. Keep it away from mouths and eyes and wash hands after the activity.

STUDENTS OFTEN SAY“More yeast must always make a taller column.”

BETTER IDEAMore catalase can speed peroxide breakdown, but the available peroxide limits how much oxygen can form; height can level off.

STUDENTS OFTEN SAY“Foam alone proves exactly which new substances formed.”

BETTER IDEAFoam and warming are observable evidence of change. A full identification of substances would require additional evidence and property tests.

08 //

Differentiation

SUPPORT

Prepare labeled yeast portions and a height scale before students begin.
Assign one student to time, one to read height and one to record the 10-second observations.
Offer the frame: “With __ tsp yeast, the foam reached __ cm in __ seconds; compared with __ tsp, it was __.”

EXTEND

Graph maximum height against yeast amount and mark the point where added yeast no longer increases height.
Repeat one condition and compare trial variation while holding peroxide and bottle setup constant.
Design a follow-up that changes peroxide amount only, with teacher approval, and predict how a reactant limit might shift.

09 //

Assessment rubric

Criterion	Beginning	Developing	Secure
Fair test	Changes several conditions or omits the yeast amounts.	Tests the yeast amounts but does not clearly match a key condition.	Compares 1, 2 and 3 teaspoons while keeping peroxide at 3% and matching the other listed controls.
Measurements	Leaves height or time data mostly blank.	Records some heights or times but omits units or the plateau rule.	Records maximum height in centimeters and plateau time in seconds from 10-second checks.
Pattern	States a result without comparing conditions.	Compares conditions but treats a prediction as guaranteed.	Uses measured height and time to describe the observed yeast-amount pattern, including a possible plateau.
Reaction reasoning and safety	Calls the foam edible or gives no evidence for a reaction.	Uses foam as evidence but omits heat, limits or a safety rule.	Uses foam and warmth as evidence, notes limits of the alignment and follows 3% peroxide, goggles, tray and open-bottle precautions.

10 //

Vocabulary

Catalyst – A substance that speeds a reaction without being used up in the overall process.
Catalase – An enzyme in yeast that speeds the breakdown of hydrogen peroxide.
Reactant – A starting substance that takes part in a chemical reaction.

Oxygen – A gas produced as hydrogen peroxide breaks down in this activity.
Plateau – A point when a measured value stops increasing noticeably.
Exothermic – Describes a process that releases heat to its surroundings.

11 //

Safety, cleanup and troubleshooting

BEFORE STUDENTS TOUCH ANYTHING

Use only 3% household hydrogen peroxide, never stronger lab or salon peroxide. Wear goggles and work over a tray under adult supervision.
The foam can be warm and overflow quickly. Keep the bottle open and hands, faces and eyes clear; do not touch, taste or call the foam real toothpaste.
Wash hands after handling and follow adult cleanup directions.

Troubleshooting: If the foam overflows, keep hands and faces clear and let the adult manage the tray cleanup. If little foam forms, check that the yeast was mixed into warm water and that the 3% peroxide and soap were measured as planned; record the actual result rather than switching to stronger peroxide. Never cap the reacting bottle.