Today was the last day of experiments with the kids for the semester, so we celebrated with volcanic eruptions and Mentos explosions in the playground. Here's what we needed for the volcanoes: homemade mini plaster volcanoes (made the week beforehand), dish detergent, baking soda, ketchup and/or food coloring, glitter (because why not), and vinegar. The kids frantically experimented with their volcanoes to get the perfect, messy eruption. Then, we set up Mentos geysers! We needed a bunch of large two-liter sodas (like Sprite, Hawaiian Punch, Coke, Diet Coke, and bubbly water) and plain Mentos candies. We placed bets (ahem, made hypotheses) about which soda would yield the greatest eruption after we dropped in a Mentos. By farrrrr, Diet Coke was the winner. What caused the Diet Coke to explode so nicely? The answer was likely the combination of sweeteners used in the soda, nucleation sites on the surface of the mint candies where carbon dioxide bubbles formed, as well as rapid sinking of the candy. What a blast!