Hello Everyone!

I hope you’re having a fabulous day.

Today I’m sharing how to use discrepant events to grab and keep the attention of your students! A discrepant event (in case you’re not familiar with the term) is a demonstration which has an unexpected turn of events. It causes your students to go “whoa!” and “How did you do that?!?” Instantly, their brains go into problem solving mode and you have their undivided attention. How great is that?!

A great example of a discrepant event is the “Balloon Kebab” where you insert a wooden skewer into a balloon without popping it.  Check out my video or keep reading to see how this is accomplished!

           

What you’ll need:

Vegetable Oil

Wooden Skewers

Small Round Balloons

Instructions:

• Blow up your balloons and release about 1/3rd of the air, otherwise your balloons may pop when punctured. 
• Tie off your balloons and set aside. 
• Pour about a tablespoon of vegetable into a container and use it to coat the wooden skewer. 
• Slowly and carefully puncture the balloon at the base where you tied it off
• Continue slowly pushing the skewer through until you reach the opposite end and puncture the balloon again
• Ta-da! Now you have a balloon kebab!

Sometime, even if you do all of the steps correctly, the balloon WILL pop. It’s no big deal! Just try again or have a back-up video or pre-made kebab handy.

Why it works:

Balloons are generally made of latex which is composed of polymer. Polymers consist of chain-like molecules which are grouped and intwined together. When the skewer punctures the balloon, the polymers are pushed aside and then wrap around the balloon again. This process is aided by the use of vegetable oil which works to lubricate the skewer and seal the punctured balloon. 

The skewer placement also plays a role in creating a successful balloon kebab. Since the balloon is filled with air, the majority of the latex is stretched evenly with equal surface tension. However, there are two points where the latex is not stretched as thin (by the tail and on the top). At these sections, it is possible to puncture the balloon without breaking the surface tension of the balloon.

I plan on recording many more discrepant event videos so let me know if there are any you would like to see! 

Good luck and have fun!

Hey Friends!

I can’t believe I’m creating my first post for Savvy with Science and I knew I wanted it to be a good one! The purpose of my blog is to provide teachers, parents, and anyone else who is interested with engaging hands-on science lesson ideas, resources, and videos! 

Today we will be investigating the mysterious substance of Oobleck. Many of you have probably seen or played with this cornstarch and water mixture in the past and know what a blast it can be!  

It’s easy to make:

1 Cup Water

2 Cups Cornstarch

1-2 Drops Food Coloring

                                                                                                                                                                      
For this lesson, I used Oobleck as my discrepant event after my students finished studying about liquids and solids. I pre-made the Oobleck and asked them to make predictions about whether it was a solid or a liquid based off of their initial observations. After making predictions, we reviewed the properties of solids and liquids and discussed how to test a substance to determine if it is a solid or a liquid. 

Solid or Liquid Test:

1.  Push test? - Can you push it? (yes- solid ; No- liquid)
2.  Pick-up Test-if you pick something up, does it all come up? (yes- solid ; no-liquid)
3.  Pour test-does it pour out smoothly, or does it just fall out in a clump? (yes-liquid ; no- solid)
4.  Shape test-does it keep the same shape?  (yes- solid ; no-liquid)

We used this recording sheet. Click to get yours!

We also did a sink and float test with a pencil, penny, paperclip, and string. Once completed, students had to determine if Oobleck was a solid, liquid, or had the properties of both! Students should be able to conclude Oobleck has both the qualities of a liquid and a solid.  

Now its explanation and discussion time! Oobleck is a simple mixture of cornstarch and water. Many centuries ago, Sir Isaac Newton proposed that fluids should flow at a predictable, constant rate. Fluids that behave this way and are called “Newtonian” fluids. An example is water. When you are in a swimming pool, water flows around you whether you are moving around quickly or slowly. Oobleck does not behave as a typical Newtonian fluid. Oobleck belongs to a class of materials known as Non-Newtonian fluids. Unlike water and other Newtonian fluids, Non-Newtonian fluids respond differently depending on how quickly you try to move them around. Examples include ketchup, mayonnaise, jelly, and cranberry sauce. See if your students can think of other Non-Newtonian fluids and how they could use Oobleck to solve a problem.

               

If you want to see this activity in action or just want to avoid the mess, check out my investigating Oobleck video starring my sister and husband. We all had a lot of fun with this and hope you do too!

Let me know if you try this out!