Totally Awesome to Watch!! This is one of the most striking science demonstrations we have seen in a long time. Place an ice cube on each of these two identical looking black blocks at room temperature. One ice cube instantly begins to melt and is totally gone in about 90 seconds. The other ice cube shows no evidence of melting whatsoever. Great for showing the difference in heat conductivity in different materials. This demo is simple enough for elementary students, yet of just as much interest to high school and university level students and educators. A truly beautiful demonstration! Set of two blocks. Read more on our Blog!