LF-25 · TEACHER LESSON PLAN

Paper towel absorbency lab

Compare paper towel products at a defined first-drip endpoint

ChemistryGrades 4–825–30 minHazard low; contain clean-water drips and dry floorNGSS MS-PS1-1

01 //

Driving question

START THE LESSON WITH THISEqual 10 × 10 cm paper towel squares begin dripping after different amounts of water added at the same pace. How does product type change the first-drip volume?

02 //

Learning objectives

Students prepare three equal 10 × 10 cm samples from each of three identified paper towel products, keeping plies as sold.
Students measure milliliters of clean water added at 1 mL every 3 seconds before the first visible drip in three trials per product.
Students compare each product's mean and range, distinguishing the first-drip proxy from retained mass and absorption rate.

03 //

Standards

Dimension	Alignment
Performance expectation	MS-PS1-1Develop models to describe the atomic composition of simple molecules and extended structures. (Partial alignment: this is the performance expectation the lab lists, but the activity compares how much water paper towel brands hold before dripping rather than building atomic models.)
Practices	SEP 4Analyze and interpret data.
Core idea	PS1.AEach pure substance has characteristic physical and chemical properties (for any bulk quantity under given conditions) that can be used to identify it.
Crosscutting	Cause and effectCause and effect relationships are routinely identified, tested, and used to explain change.

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

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 3-5-ETS1-3	Partial. Equal areas, controlled water addition, and repeat trials model a fair test, but this lesson compares material brands instead of testing a prototype against a design problem.	Open standard ↗
Texas	Science.5.1(B)	Partial. Students plan and conduct a descriptive investigation of towel properties, but the lesson's brand comparison is narrower than the full range of descriptive investigations and engineering practice in the expectation.	Open standard ↗
Florida	SC.4.N.1.1	Partial. Students conduct a team investigation and use measurements to explain their observations; the standard also includes source-based inquiry and broader explanation work beyond this short test.	Open standard ↗
New York	3-5-ETS1-3	Partial. Students control sample area, addition method, and repeat trials in a fair comparison, but do not test a model or prototype for improvement as this performance expectation specifies.	Open standard ↗
Pennsylvania	3.2.5.B	Partial. Students measure absorbency as a material property, but the examples in this standard do not name absorbency, and the lesson does not identify unknown materials from several properties.	Open standard ↗

04 //

Materials and prep timeline

PER GROUP

Three paper towel products; identify exact product and ply
Nine equal 10 × 10 cm squares (three fresh samples per product; retain plies as sold)
One clean catch tray, dried between trials
Clean room-temperature water and a 1 mL syringe or graduated cylinder
Scissors, ruler, labels, timer, recording sheet and floor-drying cloth

TEACHER ONLY

Prepare nine fresh equal-area squares, retain plies as sold, and label each exact product. Use a new square for every trial.
Add measured 1 mL increments at the center, waiting exactly 3 seconds between additions. Define the endpoint as the first visible drop passing through the underside.
Use one catch tray at a time and dry it before reuse. Work over a sink or tray, keep the floor dry, and provide a cloth for spills 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

0–4 MINPredict and define

Predict which brand may hold more water. Agree that the endpoint is the first visible drip and that water is added slowly.

4–9 MINMatch the samples

Label the exact products and prepare three 10 × 10 cm squares per product, keeping plies as sold.

9–21 MINMeasure first-drip volumes

Add 1 mL to the center every 3 seconds. Stop at the first visible drop passing through, record total mL, and dry the tray between samples.

21–27 MINRepeat and summarize

Test three fresh squares per product. Keep raw values, then calculate each mean and range (highest minus lowest).

27–30 MINCompare and clean

Compare brand averages and discuss how fiber structure and pour rate affect the result. Wipe drips and dry the floor.

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.

A measured syringe adds water to equal-size towel samples over catch trays at a fixed pace. — **Add water at a measured pace.**Use 1 mL every 3 seconds for every fresh 10 × 10 cm square; record the first visible drip.

Water droplets move through a porous network of paper fibers and narrow gaps. — **Model water movement through fibers.**The illustration represents capillary movement; thickness alone does not predict the measured endpoint.

Three paper towel products each have three fresh samples, beside a blank data sheet. — **Keep all three trial readings.**Calculate each product's mean and range; these data compare only the samples and procedure tested.

04B //

Printable shopping list

TEACHER PREP · Paper towel absorbency 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

Three paper towel products; identify exact product and ply
Nine equal 10 × 10 cm squares (three fresh samples per product; retain plies as sold)
One clean catch tray, dried between trials
Clean room-temperature water and a 1 mL syringe or graduated cylinder
Scissors, ruler, labels, timer, recording sheet and floor-drying cloth

TEACHER-PROVIDED MATERIALS + SETUP RULES

Prepare nine fresh equal-area squares, retain plies as sold, and label each exact product. Use a new square for every trial.
Add measured 1 mL increments at the center, waiting exactly 3 seconds between additions. Define the endpoint as the first visible drop passing through the underside.
Use one catch tray at a time and dry it before reuse. Work over a sink or tray, keep the floor dry, and provide a cloth for spills and handwashing.

QUANTITIES BY CLASS SIZE

Material	Per group kit	20 students	25 students	30 students
Paper towels from three products, three equal squares per product	9 squares	54 squares	63 squares	72 squares
One clean catch tray, dried between trials	1	6	7	8
Clean water and a 1 mL syringe or graduated cylinder	water for nine trials and 1 measuring tool	water for 54 trials and 6 tools	water for 63 trials and 7 tools	water for 72 trials and 8 tools
Rulers, scissors, and labels	1 of each	6 of each	7 of each	8 of each
Drying cloths	1	6	7	8
Student data sheets	1 per student	20 copies	25 copies	30 copies

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

05 //

Lesson flow

Minutes	What happens
0–4 min	Engage Predict which brand may hold more water. Agree that the endpoint is the first visible drip and that water is added slowly.
4–9 min	Explore Label exact products and prepare three equal 10 × 10 cm squares per product, keeping plies as sold.
9–21 min	Explore Add 1 mL at the center every 3 seconds. Stop at the first visible drop passing through, record total mL, and dry the tray between trials.
21–27 min	Explain Test three fresh squares per product. Keep raw values, then calculate each mean and range (highest minus lowest).
27–30 min	Evaluate Compare brand averages and discuss how fiber structure and pour rate affect the result. Wipe drips and dry the floor.

06 //

Discussion questions

1. Why must all towel squares have the same area?

SAMPLE ANSWERA larger square has more fiber and can hold more water regardless of brand, so matching area makes brand a clearer comparison.

2. Why add exactly 1 mL every 3 seconds?

SAMPLE ANSWERThe same measured rate keeps the first-drip endpoint more comparable. A different rate can change how much drains through before water spreads into the sample.

3. Does the brand with the largest first-drip volume absorb water fastest?

SAMPLE ANSWERNot necessarily. This test measures the amount added before dripping, not the speed of absorption; rate would need a different timed measure.

4. Why keep a range as well as the mean?

SAMPLE ANSWERThe mean summarizes three readings, while the range (highest minus lowest) shows how far apart the most extreme trials were. A single average can hide variation.

07 //

Common misconceptions

STUDENTS OFTEN SAY“A larger first-drip reading means faster absorption.”

BETTER IDEAThis endpoint records added water before leak-through at one fixed pace; a separate timed mass-gain method is needed for uptake rate.

STUDENTS OFTEN SAY“A bigger sample is a fairer brand test.”

BETTER IDEASample area must match because larger sheets naturally contain more fiber and may hold more water.

STUDENTS OFTEN SAY“An early drip proves the brand cannot absorb much.”

BETTER IDEAA fast pour can overwhelm a sheet. Use the same slow addition rate and first-drip definition for every trial.

08 //

Differentiation

SUPPORT

Provide pre-cut, labeled equal-area squares and a clean tray to dry between trials.
Use a 1 mL syringe with a large scale; one student adds and times while another watches for the first visible drip.
Offer: ‘Product __ readings were __, __ and __ mL; mean __ mL; range __ mL.’

EXTEND

Run more fresh-square trials per product and compare the mean and range.
Compare equal-area samples with different layer counts as a new variable while holding the addition pace constant.
Weigh dry and wet samples as a separate retained-mass follow-up after a fixed soak and drain time.

09 //

Assessment rubric

Criterion	Beginning	Developing	Secure
Matched samples	Uses different sample sizes or mixes brands without labels.	Labels brands but leaves one sample-size or tray condition unmatched.	Tests equal-area labeled samples over catch trays with a fresh square for each repeat.
Endpoint and records	Does not identify the first drip or leaves values blank.	Records some water amounts but changes addition pace or omits mL.	Adds 1 mL every 3 seconds and records three first-drip readings per product.
Mean, range and comparison	Does not summarize or names a product without data.	Calculates one mean correctly or compares values without noting variation.	Calculates each three-trial mean and range correctly and compares products using the table.
Explanation and cleanup	Claims capacity equals absorption speed or leaves spills.	Mentions fiber structure but needs reminders about drips or test limits.	Connects structure to water holding, distinguishes capacity from speed and dries the work area.

10 //

Vocabulary

Absorb – To take liquid into a material or its spaces.
First drip – The first visible drop that passes through the towel sample.
Fiber – A thin strand of material that makes up paper towel structure.
Capillary action – Movement of liquid through narrow spaces between fibers.

Mean – The sum of three trial measurements divided by three.
Range – The highest trial value minus the lowest trial value.
Capacity – A measured water-holding outcome; this first-drip proxy is not total retained mass.

11 //

Safety, cleanup and troubleshooting

BEFORE STUDENTS TOUCH ANYTHING

Add exactly 1 mL every 3 seconds; a different pace can change the first-drip reading.
Cut every product's sample to exactly 10 × 10 cm and keep its plies as sold.
Use clean water only; contain spills on the work surface and dry the floor promptly.
Do not drink test water or put used towels in your mouth; wash hands after handling wet materials.

Troubleshooting: If the dropper pace changes or the tray is wet before a trial, note the issue, dry the tray, and repeat with a fresh equal-area square using 1 mL every 3 seconds. Wipe spills promptly and dry the floor before walking.