Here in the midwestern United States, the days are getting hotter and the kids are wanting to be outside all the time! In this STEAM (Science, Technology, Engineering, Art, & Math) activity, kids will use art to learn about the sun’s role in evaporating water. It is great for little scientists of all ages!  Young toddlers can practice fine motor skills, shape and color identification, and explore their creativity, and older kids can experiment with colors, practice tracing and using timers and collect data.  (Beware, this one can get pretty messy!  Both of my children also painted their arms and legs, hair, pants, etc.) 

LEARN SCIENCE VOCABULARY:

Evaporation – the process where liquid water turns into a gas (water vapor) because of added heat.

Hypothesis – an educated guess about what will happen next in the experiment.

Data – the information that you collect during an experiment.  Data can be numerical or it can be the observations you make with your senses.  In this experiment we will have both!

MATERIALS NEEDED:

• Water
• Paintbrushes (I got large cheap-o ones from the hardware store that are easy for little hands to hold.)
• Sidewalk chalk (Save the broken pieces of chalk to color your paint, but keep a couple big pieces out for tracing.)
• Quart or gallon size zip top freezer bags
• Rubber mallet (or something similarly heavy for smashing)
• Plastic cups or bowls (old yogurt or sour cream containers would work great)
• Sunny sidewalk or driveway to paint on!
• Optional: Stopwatch or timer, if your kids are old enough to read numbers

HOW TO MAKE THE PAINT:

I saw this great recipe for sidewalk chalk paint from Rhythms of Play and thought it would be a cool way for the kids to learn about EVAPORATION!

1. Take the broken pieces of sidewalk chalk and put them into a zipper freezer bag.  (You can sort them by color if you like, or just put all the colors together and end up with a brownish purple like we did!)
2. Use a rubber mallet to smash the chalk into a powder.
3. Add water to the bag and smoosh it around to make the paint!  (If you want thicker paint, add less water.  For this activity, thinner watery paint works best so that you can see the evaporation taking place.)

   

HOW TO DO THE EXPERIMENT:

1. Pour the paint into the plastic cups and set the kids up on a sunny sidewalk with their brushes.  (You could paint big shapes and letters to practice identification and have little kids try to copy your design.  Or just let them be creative and go free-form!)

   

2. Use the larger pieces of sidewalk chalk to trace around your designs while they are still wet.  Have kids observe how the paint looks when is wet and watery on the sidewalk.
3. Watch as the heat from the sun causes the watery paint to EVAPORATE and dry up.  Observe how as the paint dries it changes color.  Was the dried up design the same size as the one you traced when it was wet?  (If you use very watery paint, the design should shrink as it evaporates.)

   

4. Find a shady spot to paint next.  Make a design that is similar to one that you painted in the full sun.  Again trace the design with the chalk.  Ask the kids to make a HYPOTHESIS: Will this design EVAPORATE more slowly or more quickly than the design in the full sun?  Why?  Watch and see if their hypothesis was correct!

NUMERICAL DATA COLLECTION OPTION FOR OLDER KIDS:

Choose one of your shapes or designs. Use a stopwatch or timer on your phone to measure how much time it takes for the water in the design to completely evaporate in the full sun. Compare this time with the amount of time it takes for the same shape or design to evaporate in the shade.  Try painting on different surfaces (like cardboard or wood) to see if that changes the time it takes for the water to evaporate as well!