Follow by Email

Friday, November 30, 2012

Cat's Meow

1. Pour 20 mL of milk into a plastic petri dish.
2. Place 4 drops of food color in milk. Vary the location of each drop. Vary the color of each drop. Neon food color works well.
3. Dip a toothpick in dish washing liquid.
4. Touch surface of milk with detergent on toothpick. Do not stir.
5. The milk will swirl. You can see this with the movement of the food color. It is fast and amazing.

Soap has a fat loving end and a water loving end. This is how soap cleanses you. The fat loving end attaches to fat containing grime. The water loving end attaches to water and rinses off of you. The movement of the milk are the attraction of fat in the milk to the soap.

You can have students test the rate of activity with skim, low-fat, whole and half and half milk. Amazingly, the skim moves the quickest.

Thursday, November 29, 2012

A Rose By Any Other Name, Oobleck is fun!

Kadinka Pink, Pabooba Blue, Latrella Yellow, Oobleck Green

A mixture of water, food color and corn starch can lead to a lot of discovery and increase interest in your classroom.

Pour a box of cornstarch into a bowl.

Add a few drops of food color. Green is usually used.

Slowly add water and knead into mixture. It has the right consistency when the mixture is hard in you hand when you squeeze your hand close and flows like a liquid when you open your hand.

As people play with the mixture, it dries. Adding more water brings it back to life. I resurrected the mixture the next day. However, keep an extra box of cornstarch and make more. It gets most foul after several classes use it.

One big point I shared with students was the fact that once everyone put their hands in the mixture, it became a germ hothouse. After the activity was completed, I shared that the cornstarch was a great source of food for bacteria, mold, etc.

This activity is incredibly messy yet easy to clean up. After all, it is only cornstarch. Cornstarch washes out of ordinary clothes. It might be tricky to get off a wedding gown. So fire your wedding planner if they suggest Kadinka Pink at any time. Use a wash cloth and bucket of water to wipe down surfaces. A bucket of water to rinse their hands before going to a sink to wash their hands.

Clean-up alert: Collect leftover Oobleck and have children stay in their seats during the activity. Reducing the amount of time students walk with oobleck reduces the amount spilled on floors or smeared on other surfaces.

Write simple observations that students can make on the board. Tests 3 through 5 below are good. Allow students to play with the mixture for about 10 to 30 minutes. Demonstrate test 3 while students are working with the mixture and the other tests after the clean-up.

1. What happens when you apply heat?
2. What happens when you leave some on a plate overnight?
Students can usually predict what will happen by the residue on desktops or lab tables.

3. What happens when you run a magnet underneath and over a plate containing Pabooba Blue.
4. Demonstrate how the material gets hard under pressure and flows when pressure is not present.
5. Test how the substance adheres to different surfaces. (Metals, plastic, cellophane, Styrofoam, wood, glass, ceramics, fired clay)

Questions and activities.
Allow students to give the substance a name. Don't settle for common names like goop, slime, oobleck, silly-putty, etc.
Have students design a spacecraft to land on the substance, collect the substance and take off from the substance.
Have students write stories about the substance.
Let students brainstorm uses. The younger they are, the more uses they will uncover. List them all. A dowager at a party asked Michael Faraday what use it was to be studying electricity? Luckily, Michael Faraday continued and you know the rest of the story.

The mixture is called a Non-newtonian fluid. Your classroom can discover the difference between a newtonian fluid and a non-newtonian fluid. Interestingly enough, glass is a fluid. This is why old window panes are thicker at the bottom and gaps often appear at the top.