Science of Oobleck

Every week, Madison (my 11-year old daughter) and I teach a 1.5-hour afterschool science club for K-2^nd graders.  Each week she helps plan the lesson and then write the blog about what we did. 

We have provided links to the books we used.  We learned a lot of the science experiments and activities from Steve Spangler (awesome speaker and science guy extraordinaire).  We have included links to his science supplies, experiments, and videos. These links take you away from the blog and to external websites.

Science of Oobleck

Science Standards Addressed:

• Identify and compare properties of pure substances and mixtures. 
• Know that changes to matter may be chemical or physical and when two or more substances are combined, a new substance may be formed with properties that are different from those of the original substances.
• Describe properties of materials in different states – solid, liquid, and gas. 

Plus we snuck in some speaking and listening standards like asking questions, expressing ideas, following multi-step directions, and participating in discussions.

As the children arrived we played the songs Green River, by Credence Clearwater Revival; and Stuck on You, by Elvis Presley. Green, sticky hints about the theme of the day!

Next we had a green snack that once again was a hint of the science to follow.

To sneak in some literacy standards, while they ate snack we read them Bartholomew and the Oobleck (1949), by Dr. Seuss.

Link to Batholomew and the Oobleck on Amazon 

This is a good story about being thankful for what you have and careful for what you wish for, by Dr. Seuss.  It’s about a king who gets tired of what comes down from the sky so he wishes for something new to come down. He asks his magicians for something new to come down, and they say they’ll make it rain oobleck. The next morning little tiny green blobs started to rain. Then they get much bigger. The oobleck gets stuck in all kinds of stuff: a horn, a nest, a bell! Bartholomew tries to warn the king, but he doesn’t care; he loves it all. Bartholomew tries to warn the people but it is too late - the oobleck is everywhere! Bartholomew scolds the king and tells the king to say that he is sorry. When the king finally admits he is wrong and says he is sorry, every thing stops and all the oobleck melts away.

(Ssshhhh! Don’t tell anyone, but this is a really long book, and the kids were anxious to start doing science, so I skipped some pages and the kids didn’t even know.)

Oobleck

Steve Spangler (famous science guy) once said to me, “Stop mixing stuff together and calling it science.”  This is exactly what often happens with Oobleck.  Oobleck has been used in many programs, but often in a superficial way – mix it up and let kids play with it.  In this activity plan we’ll kick it up a notch by taking advantage of the high interest and excitement that Oobleck creates!

We found a great resource that helped us kick it up a notch. Oobleck, What do scientists do? GEMS Teacher’s Guide for Grades 4-8, by the Lawrence Hall of Science and the University of California at Berkeley. This is a link to that book on GEMS website.  

We began by creating an imaginary situation.  We told the children that they have been asked to investigate a strange substance brought back from a previously unknown moon orbiting Mars. 

The moon is covered with what appears to be a large green ocean.  NASA sent a probe to this moon, but it was lost and what happened is unknown.  The second probe is stuck on the surface.  A third probe managed to collect a sample of the strange ocean material. 

Then we revealed a small batch of the substance that we prepared in advance.

Oobleck Recipe: Four boxes cornstarch, 6 ¾ C. water 15 drops food coloring (green makes it look like the Dr. Seuss Oobleck).  Adding the food coloring to the water rather than the cornstarch makes mixing easier.  Too much food coloring will stain hands and clothing!

Nice shirt dad!

 We explained that the material has been nicknamed Oobleck because it looks like the substance found in the book Bartholomew and the Oobleck, by Dr Seuss, and that preliminary studies have revealed that it is safe to handle.  We told them that chemists are studying the exact composition of the substance – which will be revealed to us after their preliminary examinations. 

We let them study the Oobleck and list its properties using all of their senses EXCEPT TASTE!  They skimmed their finger across the top; they sank their entire hand into it and tried to grab the fluid and pull it up. They rolled the fluid between their palms to make a ball.  They punched it and slapped it as hard as they could. 

After some time exploring the stuff, we gave them sticky notes and played, “stick it to me.” Each child wrote a word or phrase describing a property of Oobleck and then they posted their notes on us.

We asked lots of questions about how and when it behaves like a solid or liquid. What causes it to feel like something solid when you squeeze it, yet it flows like syrup as it drips off your finger?

Then Mike pretended he got a phone call from NASA.

Dorksville!

We announced that the chemists had just finished their analysis and revealed the chemical composition of Oobleck, and alas – it is composed of ingredients commonly found on earth. 

Note if you spill Oobleck on the carpet, the best way to clean it up is LET IT DRY – then scrape the powder up and vacuum. We discovered that the hard way years ago. And on that note, DON’T pour it down the drain! Or else you’ll have a mega clog to deal with. Just throw it in the trash or compost. It’s biodegradable.

Then we kicked it up another notch.  We took four 25-pound bags of cornstarch and about 10 gallons of water and mixed up the biggest batch we have done so far. Where do you get it? Restaurant supply store!

Check out Steve Spangler’s HUGE batch he did for the Ellen DeGeneres show.  Note to do this you’ll need just 2,500 pounds of corn starch and a concrete mixer! 

Oobleck  is a “non-Newtonian” substance.  It doesn’t follow the rules – Sir Isaac Newton’s rules of viscosity – that is! All fluids have a property known as viscosity. It is the measurable thickness or resistance to flow in a fluid.   Newton stated that only altering the fluid’s temperature could change the viscosity of a fluid. For example, motor oil or honey flows more easily when you warm it up and becomes very thick when it gets cold. So, a Non-Newtonian fluid has the same dependence on temperature, but applying pressure can also change its viscosity. Newtonian fluids such as water or vegetable oil are those whose viscosity does NOT change as a result of sheer force exerted upon it. 

Oobleck sometimes acts like a solid and sometimes like a liquid depending on how it is treated.  When it is under pressure, it behaves like a solid, but when not under pressure, it behaves as a liquid.  Quicksand is another non-newtonian fluid which is why struggling hard to get out of quick sand makes it more difficult to move. When you squeeze a handful of Oobleck, its viscosity increases so it acts like a solid for a split second. When you release pressure or decrease the SHEER FORCE, it behaves just like a liquid.  

Toothpaste and catsup are non-Newtonian, but they show LESS viscosity under pressure.  When I think of viscosity, I always remember the television commercial of the child who is patiently waiting for the catsup to flow out of the bottle and onto the hamburger bun. Be thankful that the viscosity of catsup is greater than that of water the next time you are sitting across the table from somebody who is pounding on the bottom of the catsup bottle. 

Coolest thing ever - scientists STILL cannot totally explain why Oobleck doesn’t follow the rules. That’s a great thing for budding scientists to hear! 

Oobleck is a “suspension” not a “solution.”  The starch does not dissolve in water, but is merely suspended in water.  Scientists have 3 educated guesses or theories about Oobleck behavior. 

The “sand in water” model argues that like sand in water, the “grains” of cornstarch are packed so closely together with little water between them so that when you squeeze gently the starch grains slides against each other and water lubricates this, but when you squeeze quickly there is not enough water in the spaces and friction causes the grains of sand to resist the flow.

The “long chain” model bases its explanation on the long chain shape of the starch molecule – they look like worms under a microscope.  This model argues that when the mixture of starch and water is pushed hard the chains are stretches in a direction that is at right angles with the push, so the long molecules get “tangled” and resist the push. 

In the “electric charge” model the explanation is that the molecules of Oobleck acquire an electric charge as they are rubbed together, the faster the rub, the more electrical attraction is created which makes the Oobleck more viscous – the molecules hold together and resist the push.

How can you throw an engineering challenge into a study of Oobleck? Kick this up notches previously unknown to mankind by including a spacecraft design contest!  We actually studied the real Mars landers and talked about the scientists who design real spacecraft.

You’ll need lots of old newspapers, masking tape, green food coloring, cornstarch, measuring cup, mixing bowl, water, paper towels, and a collection of stuff (tooth picks, popsicle sticks, plastic utensils, paper clips, packing peanuts, straws, paper cups, etc.)

Their challenge is to design a spacecraft that is able to land safely on an ocean of Oobleck without sinking and take off without getting stuck using only the materials provided. Have them draw their plans on paper using the collection of materials you have provided and then give them time to build and test their spacecraft.

How could you sneak in even more literacy?

Kids can make up stories about creatures who live on the moon with the green Oobleck oceans.  How do they survive?  What is the weather like?  What do they eat?  What do they look like?  What are their customs?  What do they think of Earthlings?