LF-19 · TEACHER LESSON PLAN

Oobleck non-Newtonian fluid lab

How this cornstarch suspension responds to gentle sinking and quick force

ChemistryGrades 3–820 minHazard low; messy mixture and drain blockageNGSS MS-PS1-1

01 //

Driving question

START THE LESSON WITH THISHow does the ratio of cornstarch to water change how fast a marble sinks into the mixture?

02 //

Learning objectives

Students prepare fresh mixtures at 1:1, 1.5:1 and 2:1 cornstarch-to-water ratios using the same measuring method and stirring time.
Students measure three five-second marble depths in separate spots of each batch, then calculate a mean and range; log one separate qualitative tap observation.
Students explain how a cornstarch suspension can resist rapid force yet flow under gentle force, without treating it as a pure substance.

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 investigates a suspension that behaves differently under slow and fast force 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 5-PS1-3	Partial. Students measure a material response, but this standard concerns identifying materials by their properties; it does not assess how a cornstarch suspension responds to force speed.	Open standard ↗
Texas	Science.5.6(B)	Limited. Oobleck is a mixture, but this investigation measures its response to gentle and quick force rather than demonstrating that a mixture's ingredients maintain their separate physical properties.	Open standard ↗
Florida	SC.8.P.8.4	Partial. Students observe a physical response of a suspension, but they do not classify samples using the standard's full set of characteristic properties.	Open standard ↗
New York	NYSSLS MS-PS1-8	Partial. The activity investigates a cornstarch-water mixture, but it does not demonstrate the full range of mixture separation or analysis described by the standard.	Open standard ↗
Pennsylvania	STEELS 3.2.2.A	Partial. Students investigate observable properties of a mixture, while the grade-two expectation is a simpler material-classification task and does not address non-Newtonian behavior.	Open standard ↗

04 //

Materials and prep timeline

PER GROUP

Cornstarch and water measured by volume: 75 + 75 mL, 90 + 60 mL, and 100 + 50 mL for 1:1, 1.5:1 and 2:1 ratios
Three identical wide shallow trays for 150 mL batches
Same clean marble, millimeter ruler and timer
Stirring spoons, ratio labels and recording sheet
Covered table, scraper and waste container for drying mixture

TEACHER ONLY

Measure each ratio with the same volume method and stir each batch for the same time until no dry pockets remain.
Mark three separated untouched spots in each tray. Use the same clean marble, gently place it, and measure from the original surface to its lowest point at exactly five seconds. Retrieve it and repeat at the next spot; record every reading and any bottom limit. These repeated spots share one batch and are not independent recipe preparations.
After depth readings, use a separate spot for one quick tap with the same tool. Keep this qualitative observation separate from the slow marble measure. Keep all mixture out of sinks and drains; scrape it into waste to dry, then discard the solid. Do not eat the mixture.

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

0–3 MINPredict and review

Predict how increasing the cornstarch-to-water ratio may affect a gently placed marble. Review the covered tray and strict no-drain disposal rule.

3–8 MINMix three ratios

Measure 1:1, 1.5:1 and 2:1 cornstarch-to-water batches into matching containers. Stir each for the same time until no dry pockets remain.

8–14 MINMeasure three untouched spots

Use the same clean marble in three separate spots per ratio. Measure the depth below the original surface at exactly five seconds and keep all nine readings. Mark any result limited by the tray bottom.

14–16 MINTest a separate quick tap

Use one untouched spot per ratio and the same tool for one quick tap. Record the observation without treating this as a measured force.

16–20 MINCompare and clean

Calculate each batch's mean and range, compare with its tap note, and explain the limitations of repeated spots from one batch. Scrape mixture into waste rather than the drain.

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.

Cornstarch-and-water mixture flows slowly from a scoop but resists a quick touch in a holographic lab scene. — **Oobleck responds differently to slow and quick motion.**This shear-thickening suspension can flow under slow movement and resist rapid deformation over the tested conditions.

A particle-level infographic contrasts cornstarch grains shifting under slow shear with temporary crowding under rapid force. — **The suspension resists rapid deformation temporarily.**Cornstarch particles dispersed in water can crowd and jam when forced together quickly, while slower movement lets them shift past each other.

AI-generated classroom illustration titled Oobleck: Slow Flow, Fast Force, comparing a fingertip slowly sinking into the mixture with a light quick tap that briefly meets resistance. — **Oobleck responds to how quickly it is moved.**A gentle slow touch sinks into the suspension, while a quick light tap briefly meets resistance. The measurement table below records the separate marble-depth trials.

04B //

Printable shopping list

TEACHER PREP · Oobleck non-Newtonian fluid 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

Cornstarch and water measured by volume: 75 + 75 mL, 90 + 60 mL, and 100 + 50 mL for 1:1, 1.5:1 and 2:1 ratios
Three identical wide shallow trays for 150 mL batches
Same clean marble, millimeter ruler and timer
Stirring spoons, ratio labels and recording sheet
Covered table, scraper and waste container for drying mixture

TEACHER-PROVIDED MATERIALS + SETUP RULES

Measure each ratio with the same volume method and stir each batch for the same time until no dry pockets remain.
Mark three separated untouched spots in each tray. Use the same clean marble, gently place it, and measure from the original surface to its lowest point at exactly five seconds. Retrieve it and repeat at the next spot; record every reading and any bottom limit. These repeated spots share one batch and are not independent recipe preparations.
After depth readings, use a separate spot for one quick tap with the same tool. Keep this qualitative observation separate from the slow marble measure. Keep all mixture out of sinks and drains; scrape it into waste to dry, then discard the solid. Do not eat the mixture.

QUANTITIES BY CLASS SIZE

Material	Per group kit	20 students	25 students	30 students
Cornstarch	265 mL measured by volume	1,590 mL	1,855 mL	2,120 mL
Water	185 mL	1,110 mL	1,295 mL	1,480 mL
Matching wide shallow trays	3 trays	18 trays	21 trays	24 trays
Clean marble	1 marble	6 marbles	7 marbles	8 marbles
Ruler and timer	1 set	6 sets	7 sets	8 sets
Tray, scraper and waste container	1 cleanup set	6 sets	7 sets	8 sets
Student recording 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
0–3 min	Engage Ask how cornstarch-to-water ratio may change marble sinking. Predict first and review that oobleck must never go into a sink drain.
3–8 min	Explore Measure 1:1, 1.5:1 and 2:1 batches in matching containers. Stir each mixture for the same time until no dry cornstarch pockets remain.
8–14 min	Explore Use the same marble in three separate untouched spots per ratio. Record each depth after 5 seconds and note whenever it reaches the bottom.
14–16 min	Explain Use the same tool for one quick tap on a separate spot and record only the qualitative response; do not call it a calibrated force.
16–20 min	Evaluate Calculate the three-reading mean and range for each batch, then explain what these repeated spots can and cannot show. Scrape mixture into waste to dry; never pour it down a drain.

06 //

Discussion questions

1. Why can oobleck feel firm when tapped but flow when left alone?

SAMPLE ANSWERThe cornstarch particles can jam together under a sudden force, briefly resisting flow. With gentle force they have more time to move past one another in the water.

2. What do three readings in separate spots tell you?

SAMPLE ANSWERThey show how readings vary within that prepared batch and allow a mean and range. Because they share one recipe preparation, they are not independent batches; repeat the whole preparation per ratio to strengthen the evidence.

3. Why might a 1:1 mixture behave more like a liquid than a 2:1 mixture?

SAMPLE ANSWERIt has more water relative to cornstarch. A higher particle concentration often resists a quick tap more strongly, though mixing and ingredient measurements also matter.

4. Why can no oobleck be poured down a drain?

SAMPLE ANSWERCornstarch settles and can collect in plumbing, where it may harden or block the pipe. Scrape it into waste, let it dry and discard it in the trash.

07 //

Common misconceptions

STUDENTS OFTEN SAY“Oobleck is a liquid in one test and becomes a solid substance in another.”

BETTER IDEAIt remains a cornstarch-and-water suspension; its resistance to flow changes with the speed of the applied force.

STUDENTS OFTEN SAY“More cornstarch always means the marble cannot sink.”

BETTER IDEAA higher ratio may slow sinking or resist a quick tap, but use the measured 5-second depths and note container limits.

STUDENTS OFTEN SAY“Oobleck can be rinsed into the sink with plenty of water.”

BETTER IDEACornstarch can clog plumbing. Scrape the mixture into a waste container, let it dry and throw the solid away.

08 //

Differentiation

SUPPORT

Pre-label three containers with 1:1, 1.5:1 and 2:1 ratios and prepare ratio measuring cards.
Use a visible 5-second timer and a ruler held against the transparent side of the container to read depth.
Offer the frame: “At __ ratio, the marble sank __ mm in 5 s; when tapped, the mixture __.”

EXTEND

Repeat the marble test at each ratio and compare repeated depths before making a claim.
Change only the tap speed in a follow-up and describe how the response differs from gentle placement.
Test whether a larger marble changes depth while keeping ratio, container and placement method constant; record when it reaches the bottom.

09 //

Assessment rubric

Criterion	Beginning	Developing	Secure
Ratio preparation	Does not label ratios or changes measuring methods.	Prepares labeled mixtures but leaves stirring or container conditions unmatched.	Prepares 1:1, 1.5:1 and 2:1 batches with the same volume method, stirring time and container setup.
Marble measurements	Leaves the sink-depth table mostly blank.	Records some depths but omits the five-second endpoint or millimeters.	Records all three five-second depths per ratio in millimeters, calculates the mean/range, and notes any bottom limit and shared-batch limitation.
Tap comparison	Does not compare the tap test with slow sinking.	Records a tap response but leaves the method or observation unclear.	Uses one quick tap on a separate spot and records whether it feels solid or splashes like a liquid.
Explanation and disposal	Calls the mixture a new pure substance or rinses it into a drain.	Explains one behavior but misses the force-rate difference or cleanup rule.	Explains resistance under quick force versus slow flow and scrapes the mixture for drying and trash disposal.

10 //

Vocabulary

Suspension – A mixture with particles distributed through a liquid that can settle over time.
Non-Newtonian fluid – A fluid whose resistance to flow changes when the applied force or speed changes.
Shear thickening – An increase in resistance to flow when a suspension is forced to move more quickly.

Ratio – A comparison of amounts, here measured cornstarch volume to water volume.
Depth – The distance the marble moves below the mixture surface.
Control variable – A condition kept the same while testing the mixture ratio.

11 //

Safety, cleanup and troubleshooting

BEFORE STUDENTS TOUCH ANYTHING

Do not eat or breathe dry starch. Mix gently over a covered tray and wash hands.
Never drain oobleck; let it dry and put it in trash. Wipe spills to prevent slips.

Troubleshooting: If a batch is too dry to flow, add a small measured amount of water and record the adjustment; if too runny, add a small measured amount of cornstarch and record it. Do not compare an adjusted batch as if its original ratio were unchanged. Scrape all mixture into a waste container to dry; never rinse it down a drain.