This is a fun and simple, classic little science experiment to do with your kids. You can see from the video that all ages will still get a kick out of the spewing foam (even the videographer). I had ripped this experiment out of a Today’s Parent magazine years ago. Having just moved last month, I found it as I was unpacking. Just as I was about to file it in the ‘crafts to do but who’s kidding who we’ll never get to it’ pile, I forced myself to prepare the craft right then and there. So, when my kids came home from school and ski programs later that day, all the required materials were on the table. Instant fun and I get to scratch something of my list of things to (eventually) do.
Most bottle sizes will work. Smaller bottles will just have more overflow. We used a 20 oz bottle (2 1/2 cups).
Food colouring – we don’t own any. I get creative at easter and times like this and use natural colours. We had water colours out on the table already from the slime craft that was going on earlier that morning (that post coming next), so we simply oversaturated one colour with water to really pick up the colour, and added it to the vinegar. Was super simple and it produced a nice lavender colour.
fun foam
WHAT YOU WILL NEED:
• clear bottle
• 1 tsp baking soda
• generous squirt of liquid dish soap
• pan with sides
• colouring (watercolour paint or any vegetable or fruit dye)
• 1 c white vinegar
EASY STEPS
Ask one of the kids to put 1 tsp baking soda and the liquid soap into the bottle, and put the bottle in the pan.
Ask another child to add some colour to the 1 c of vinegar.
Pour the coloured vinegar into the bottle and watch the foam spew out.
When the foaming stops you can add another tbsp of baking soda and vinegar to reactivate the action.
WHY DID THAT HAPPEN
Combining baking soda and vinegar creates a chemical reaction that produces carbon dioxide gas. Combined with the soap, the gas bubbles makes the foam spew out of the bottle.
Enjoy! 
