Objective:
Explore evaporative properties of water in the desert through creative outdoor painting.
One characteristic of a desert is a dry climate with a relatively high rate of evaporation. This is especially true for the Sonoran Desert, which in some cases, small amounts of precipitation are only present for a short time before “disappearing” and returning to a gaseous state. A simple way for young children to experiment with evaporation is through painting with water in an outdoor setting. Grab a paintbrush, and uncover what the desert can teach you.
Materials:
- Large paintbrush
- Container of water
- Smooth semipermeable surface, such as flagstone or concrete
- Timer
Select your surface. Set up your materials in your preferred outdoor space. A large, open area on concrete patios and sidewalks make an ideal studio for painting with water.
Paint a design. Keep it simple—try a heart shape or an outline of a cactus.
Watch and wait. Take a step back after a moment. What do you and your child observe? Use a timer to record the amount of time it takes the painted design to evaporate completely.
Make it a contest. Hypothesize together ways to increase the amount of time it takes to evaporate and beat your original time. Test it out, and see if you are correct. Next, try the opposite. What can you change about your painting to make it evaporate faster?
Let your child lead the way. In the right environment, children instinctively experiment with materials in order to learn more about them. Help your child along the way, and stand back to let them paint watery creations and enjoy their own discoveries.
Extension:
How does temperature effect evaporation rate? Try this experiment in the early morning in cooler weather, then again in the heat of the afternoon.
