Have you ever seen an egg squeeze through a milk bottle? Show your class this experiment to illustrate expansion and contraction. Where else do we see these at work?

Nearly 400 years have passed since the thermometer was first created! But guess what? The principles are still the same. It works based off of expansion and contraction. Have small groups create thermometers and test them out in...

This lesson will go into more detail describing how a muscle contracts. It is 1 of 4 in the series titled "Muscle Contractions: Micro Level."

Hank calls in a friend to do his push ups for him today to explain how skeletal muscles work together to create and reverse movements. Hank and Claire also demonstrate the role size plays in motor units, the three phase cycle of muscle...

A brief audiovisual presentation that explains what an apostrophe is and its three main uses [3:22]

A screencast lesson introducing contractions and explaining how to use apostrophes when forming contractions. [2:56]

In this cool science experiment, you will see how you can put a balloon directly into a candle flame and the balloon will not burst. The power of heat conduction makes this possible. Have fun while learning about heat transfer and energy...

David and Paige, KA's resident grammarians, introduce a new piece of punctuation: the apostrophe!

Apostrophes are great at standing in for missing letters, allowing us to shorten words. Paige and David discuss contractions and the Principle of Least Effort.

Contractions are easy when you use this song to help you remember how to form them.

Learn this simple contraction with this clever song.