She mixed baking soda, water and green food coloring into little mounds and froze them several hours. Oh, she also hid a little "gold" inside.
At the appointed hour she pulled out the pan of frozen rocks and had students pick a favorite to set inside a shallow basin that had previously been "greased" with dish soap. Once the rock was in the basin the students used long straws to transfer small amounts of white vinegar for dripping over the rocks--foam city!!! The dish soap enhanced the foaming effect and it kept growing and growing as each successive student took their turn.
The gold inside gradually showed up as the rocks melted away--lucky gold for St. Patty's Day!
|The rocks turn blue in the freezer, then revert to green when they warm up.|
|Drip small amounts of vinegar onto the lucky rocks.|
|Wait for the magic foam to dissolve the rock and reveal the gold.|
|Okay, the gold turned out to be a tiny bell. It's hard to find lucky gold coins at the store the day before the holiday!|
|What a great texture to explore, and so cold!|
|Same materials--three different student styles. For this version the student dipped the eraser of a pencil into the paint for a stippled effect.|
|Looks like wide brushstrokes.|
Happy St. Patrick's Day to all! I'll be wearing the green all day!