Magic Breaking Pencil: Light Refraction Science for Kids

When it comes to science, things don’t always have to be complicated. Some of the most meaningful science experiments have just a few steps and supplies, just like this science experiment on water refraction. The magic breaking pencil activity is a fun way to demonstrate how light waves work with kids and will provide tons of fun on a lazy summer day or any time of year.

Fill a glass halfway with water and half with oil.

Tell your kids you will break the pencil, using nothing but your mind.

Lower the pencil in the water, then slowly rotate it until it looks broken from the side.

Your kids will be surprised you broke the pencil if they are young, but older kids aren’t so easily fooled.

Tell the kids you will also magically fix the pencil and slowly raise it out of the glass, revealing that it is whole once again.

After this dramatic demonstration, talk about light refraction and why a pencil will look broken when placed in oil and water.

Try the experiment with other objects and see if you can “break” them too!

THE SCIENCE LESSON

A light wave travels through a medium using a process known as refraction. Light waves can travel through objects like air, water, oil, and glass, but not through a pencil itself. Light is refracted differently through oil than water, which is why the results are more dramatic with a glass filled with half oil and half water. The light waves travel fastest through air, a little slower through water, and the slowest through oil. That is why the pencil looks so dramatically broken when you move it through the glass and look at it from different angles. You can magically “fix” the broken pencil by changing where the pencil is positioned in the glass.