Middle School Science Lessons

Here is a simple experiment to incorporate making predictions and reading graduated cylinders. I have two 1-Liter graduated cylinders set up, one in a glass cylinder with blue food coloring and one in a plastic graduated cylinder with green food coloring. I also add a few drops of rubbing alcohol or iodine to keep it from getting too funky over the length of the school year.

I filled both with water a few days before the start of school and an equal amount of drops of food coloring. Students will make predictions on small post-it notes (Name and volume in mL) and place it on to the drawing of a large graduated cylinder.

• Where do they think the water level will be at the end of school?
• Will it evaporate before school ends?
• If earlier than June, by what date?

I will also have them come up with factors that affect the rate of evaporation on larger post-it notes. What affects evaporation? Will the air in our classroom be drier in the Winter when the heat is on? Is our classroom humid now since it is warm out?

As the year goes on, I draw a meniscus of where the water level is on the first school day of each month. They love to check it out after holiday breaks, too.