Bubbling Witch's Brew Foam

What you need

• Baking soda, 3 big spoonfuls
• White vinegar, 1/2 cup to start, plus more added gradually
• Food coloring, a few drops of green or orange
• Dish soap, a squirt
• Plate or tray, 1 tray
• Bowl, 1 large, or a pot
• Wooden spoon, 1
• Clear cups, 1 small cup
• Towel, 1 old towel, or newspaper
• Measuring cup, 1

How to do it

Grown-up prep: Set out everything on a table or floor you do not mind getting wet. Remind kids the brew is for looking and stirring, never for tasting.

1. Set your cauldron bowl in the middle of the tray.
2. Spoon the baking soda into the bottom of the cauldron.
3. Drip in a few drops of green or orange coloring.
4. Squirt in a little dish soap for extra bubbles.
   Ask: What do you think soap will do to our brew?
5. Stir with the wooden spoon and say a silly spell!
6. Pour in the vinegar and watch the foam rise!
   Ask: What do you see, hear and smell?
7. Guess what is making all those bubbles.
8. Pour in a splash more vinegar to make it bubble again!
9. Now cook up another brew! Can you make it even bigger or a new color?
   Ask: What would you change to make the biggest foam of all?

Play it again

• Color mix: use two colors in the bowl and see what the foam turns into.
• Foam race: make two cauldrons with different amounts of baking soda and see which foams higher.
• Potion lab: use small clear cups and make a tiny brew for each toy or friend.