If you’re still wondering what to make for grandmas, moms, aunts, or any other special mother-figure this mother’s day, Travis and I have got you covered with this treat for the toes from Highlights magazine. The gift is equal parts craft and science, which makes it a fantastic way to engage kids in the spirit of gift-giving.

In a large craft bin, Travis mixed up the following ingredients:

1 cup baking soda

1/2 cup citric acid

1/2 cup Epsom salts

3/4 cup corn starch

Make sure to tell your child that the mixture isn’t edible, even though most of the ingredients are, especially if you’re used to cooking together!

In a small bowl, we whisked together 2 tablespoons olive oil and 1 tablespoon water. Add the liquids to the mixture slowly, stirring until combined. Kids will want to wear goggles (or sunglasses, in a pinch!) to protect their eyes, since it will bubble as you stir.

We also added blue food coloring for a pretty tint and a few drops of vanilla extract for a nice smell. The downside was that this made our mixture a little too liquidy (you want it to be slightly dry and crumbly). It seemed all right at first, but as our bath bombs dried, they puffed out. Note Travis in his too-cool-for-school sunglasses, ha!

Use an ice cream scoop to scoop out each portion, and pack down tightly. Gently release onto a paper towel and let dry for a full 24 hours.

Package the bath bombs in any pretty tissue paper or parchment paper.

We also added a little gift tag with instructions for treating those tootsies!

And of course we saved one to test out at home! Travis loved watching it fizz, before putting his feet in to soak. Don’t forget to give a quick explanation of why it all fizzes up – the baking soda and citric acid reacting together once in water, of course, which releases CO2 gas (ergo, bubbles).