Running MinecraftEDU, I'd rather my students get blowing stuff up out of their systems safely in singleplayer mode where they can't mess up anyone else's work. The problem is, while in single player mode, the TNT block just blinks for a bit then disappears after it's been set to explode. There's no explosion and no blocks are affected. There doesn't seem to be any setting in single player to turn TNT off. Lava flows and fire spreads, but no TNT explosions. Any way to change this?