Volcano Hill

 We have a large mound of dirt in our yard, and I thought it might be the perfect place to try out our volcanoes, as I didn't want to repeat the inside explosion. Desert Girl was happy to dig.

Desert Boy was given the task of burying some plastic bottles, aka magma chambers.

 Then his friend Neto came over to help with the volcano eruption. I mixed a little food coloring in with the vinegar to give it some extra oomph.

 I never did find the exact proportions of baking soda to vinegar we were supposed to be using, so I just guessed. I also had the kids make a "forest" on the hill.

 Eruption time! Looks like the forest was spared.

That was so much fun we had to do it again and again until we had used up all the baking soda and vinegar.

 A few days later, after resupplying, Ava came over and we had to show her volcano hill.

 The kids were looking forward to what would happen.

 Ava and Desert Girl don't look so sure about the eruption, but Desert Boy is clearly enjoying the mess.

We kept going with more explosions. We are still trying to perfect the technique and see a two-foot high explosion. So if you have any ideas, let us know. In the meantime, we'll keep experimenting. It's nice to be outdoors!