Just so that Valentine's Day doesn't get too pink, frilly and mushy, I like to throw an explosion in the mix. Well, not quite an explosion, more like an eruption. The link is that Valentine's and volcano both start with V. So, I figure it's all good. And there's always room for a good eruption. Both these books have amazing photographs of actual eruptions. The Simon Seymour book includies some before and after photos of Mount St. Helens in Washington State.
This was the best Youtube clip that I found.
The first eruption, I already had the baking soda inside the volcano (a recycled glass juice bottle taped onto an upturned plastic flower pot, padded with newspaper and covered with a black garbage bag). I poured in the vinegar and we all enjoyed the eruption. Then we made science out of the "magic". I explained how baking soda is a base and vinegar is an acid, and that bases and acids don't get along and when they are put together they explode. Hopefully that very "kindergarten explanation" will help them in grade 10 chemistry!