Frozen Fizzy Chalk
Here’s a fun way to play with chalk and enact a science experiment at the same time. Frozen fizzy chalk is easy to make and is the perfect activity for a hot summer afternoon. Make as many colors and shapes as you like, and store them in the freezer for a sunny day.
DIRECTIONS
1. Pour baking soda into a bowl or cup. Measuring cups work well because the mixture can be poured more easily when it’s finished. Add cornstarch, and pour in water. Stir to combine. Add dish soap, if using.
2. Tint the mixture with the color of your choice. The chalk will lighten as it freezes, so use plenty of color and stir well.
3. Pour into an ice cube tray or mold. If the cornstarch and baking soda have settled to the bottom, stir to reincorporate before pouring.
4. Place in the freezer until the chalk is frozen solid. Remove the frozen fizzy chalk from the molds. Because the chalk mixture expands slightly as it freezes, you might find that it will come out more easily after sitting at room temperature for a few minutes.
5. Fill a spray bottle with vinegar.
6. Place the frozen chalk pieces on a driveway or sidewalk. Spray with vinegar, and watch them fizz and bubble!
7. You can also use it to make colorful drawings just as you would regular chalk. The color will become more vibrant as it dries. As it begins to melt you can also mix the colors together.