Lava stands on TNT

I made a tower from TNT, I put sand on the tower, I put 2 pieces of TNT on the sand, I put lava on those 2 TNT on the very top. When all the bottom TNT exploded and the sand fell down, I put a block under the TNT, then I put a lever on the block and then I turned the lever, then the TNT exploded. And then its done. The tower with sand needs to be very long. That's what she said.