Kansas College and Career Ready Standards

• HS-PS1-3. Plan and conduct an investigation to gather evidence to compare the structure of substances at the bulk scale to infer the strength of electrical forces between particles.
• HS-PS2-6. Communicate scientific and technical information about why the molecular-level structure is important in the functioning of designed materials.
• HS-PS1-5. Apply scientific principles and evidence to provide an explanation about the effects of changing the temperature or concentration of the reacting particles on the rate at which a reaction
  occurs.
• HS-PS2-3. Apply scientific and engineering ideas to design, evaluate, and refine a device that minimizes the force on a macroscopic object during a collision.
• HS-PS3-2. Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as a combination of energy associated with the motions of particles (objects) and energy associated with the relative position of particles (objects).
• HS-PS3-3. Design, build, and refine a device that works within given constraints to convert one form of energy into another form of energy.

Learning Objectives

After completing these activities the student will be able to:

• To observe and discover the unique properties of cornstarch
• To design experiments that determine the viscosity of everyday fluids
• To develop models to better understand how microscopic behavior influences macroscopic properties
• To take unique concepts and properties and apply them to real world applications

Materials

For the Instructor:

• CornSTARch PowerPoint
• Bucket with water to wash hands
• Pitcher(s) of water
• Bucket or container of cornstarch (no label)
• Paper towels
• Trash bags
• Hammer
• Wood block and nails
• Large baking pan, tub or similar container filled with premade Oobleck mixture
• Large baking pan, tub or similar container filled with water or vegetable oil

For Each Student:

• 3-5 ounce paper or plastic cup
• Popsicle stick
• Safety glasses
• Mystery Mixture Observation Sheet

Safety Considerations

• Wear appropriate clothing for the weather and outdoors.
• Students should wear safety glasses.
• Any mixture that ends up on clothes can be easily washed away with water.
• Any mixture that ends up on the ground can be rinsed with water or washed away in the rain.
• Be very careful with the hammer when hitting the mixture or the nail into the wood.
• Be sure to throw out mixture at the end of the day. The cornstarch is a great food source for microorganisms.

Procedure for Lab

• Do not tell students the name of the mixture or the name of the mystery powder.
• Give a quick explanation on how to fill out the Observation Sheet.
• Give a quick explanation on how to make the mystery mixture.
• Have students help take the buckets of water, paper towels, trash bags, pitchers of water, the large batch of Oobleck and the hammer, block and nails outside the building.
• Students should wear safety glasses.
• Have students play with the mixture, let them explore and discover.
  • They can stir it slow and then fast.
  • They can pour it in their hands and play with it.
  • They can toss it in the air and catch it, or play “hot potato” with a classmate.
  • They can place it on the ground and hit it with a hammer.
  • Throw it against the wall (with permission!)
  • They can put their hands in the large baking pan mixture and squeeze it and scratch it.
  • They can place the wooden block on top of the mixture in the baking pan and try to hammer nails into the block.
  • Have students compare the properties of the mystery mixture with the properties of water from the buckets or pitchers.
• When finished students can throw away the mixture, cups, paper towels and popsicle sticks into a trash bag.
• Students can rinse off their hands in the wash bucket outside and then wash their hands in the bathroom on the way back to class.
• Have students fill out their Observation Sheets.
• Use the rest of the class time for discussion.

Background Information

• This is an exploration, discovery activity.
• Background information can be found in the CornSTARch PowerPoint presentation.
• Newtonian Fluid – A fluid that responds linearly to a force. If a force is applied twice as hard, the fluid should move twice as fast. Examples – water, oils, and alcohols.
• Non-Newtonian Fluid – A fluid that responds non-linearly to a force. If a force is applied, the fluid will respond by getting thicker and more solid-like or thinner and more liquid-like.

Procedures for Instruction

Length of Time for Preparation: 30 minutes for planning lesson, setup and making cornstarch mixture (Oobleck).

Length of Time for Classroom Teaching:50 minutes for discovery activity and discussion.

Preparation Procedure

• Print out copies of Mystery Mixture Observation Sheet for each student.
• Make a large batch of Oobleck in a large baking pan or similar container.
  • For every ¾ cup cornstarch add about ¼ cup water
  • Or add about 1/4 to 1/3 the amount of water compared to the amount of cornstarch.
  • Mixture should have the consistency similar to that of school glue.
  • Adjust with more water or cornstarch as necessary to get proper consistency.
  • The popsicle stick should easily move through the mixture when going slow and harden up when the popsicle stick tries to move fast. It will harder when you try to stab the mixture with the popsicle stick.
• Practice hammering a nail through a wooden block placed on top of the Oobleck mixture.
• Fill a bucket or multiple buckets with water. This will be used to have students wash their hands before going back inside the building.
•  Fill pitchers with water. Students will use this water to make their mixture.
• Fill a couple containers or small buckets with cornstarch (no labels, it’s a mystery!) and a spoon.
• Have plenty of paper towels available and a couple of trash bags.

Viscosity Trials

• Off to the Viscosity Races (pgs. T 7 – T 9)
• Graduated Cylinder Viscosity Test (pgs. T 10 – T 12)
• Viscosity Cup Test (pgs. T 13 – T 15)
• Oobleck Form and Function (pgs. T 16 – T 18)

Classroom Discussion

• What properties did this mystery mixture display?
• Were any of these properties surprising? How so?
• What is the mystery powder?
• What applications can this mixture (or mixtures with these properties) be used for?

Extension Activities

• Mystifying Mysterious Mixture: (pg. S1)
• Disco Dancing Oobleck: Using a speaker box with a subwoofer, certain frequencies will make it dance!
  (pg. S2 – S3)
• Perfect Oobleck Ratio: Students will determine the “perfect” ratio of cornstarch to water by
  experimentation. (pg. S4 – S5)
• Oobleck Inc.: Students will design and market a product that utilizes the properties of a Non-Newtonian
  Fluid. (pg. S6 – S7)
  • Students can create a working prototype of this product.
  • The marketing presentations can be done in a “Shark Tank” style.
• Oobleck Egg Drop Challenge: Have students design a system that uses Oobleck to protect an egg
  from a drop. (pg. S8 – S10)

Teachers Resources

Teacher Tips

• Cornstarch and the Oobleck mixture are very MESSY. But, it easily washes out of clothes, carpets, etc.
• It is fine for the mixture to fall on the grass or the sidewalk. It washes away easily.
• Feel free for you or your students to come up with different ways to test the properties of this mixture.
• Have students list mixtures or substances that have similar properties to Oobleck.
• Have students brainstorm and list applications for a mixture with these properties.
• Have students compare the properties of Oobleck with other substances such as water, oil, honey, ketchup, etc.
• Have students experiment the perfect ratio of water to cornstarch.

Reflection and Conclusion

• Have students list all of the properties they came up with on a whiteboard at the front of the room.
• Discuss how cornstarch is used in baking.
• Discuss how observation of the world around them is the first step in the scientific process.

Assessments

• Students should have the Observation Sheet filled out with thoughtful and thorough observations.
• Students should be able to explain how the scientific process was used in discovering the properties of Oobleck.
• Students should be able to list many different properties used during observation to describe matter.

Disclaimer

Any educator electing to perform demonstrations is expected to follow NSTA Minimum Safety Practices and Regulations for Demonstrations, Experiments, and Workshops, which are available at https://static.nsta.org/pdfs/MinimumSafetyPracticesAndRegulations.pdf, as well as all school policies and rules and all state and federal laws, regulations, codes and professional standards. Educators are responsible for abiding appropriate legal standards and better professional practices under a duty of care to make laboratories and demonstrations in and out of the classroom as safe as possible. If in doubt, do not perform the demonstrations.