Float or Sink

In connection with this week's unit on Noach, we did a scientific experiment on buoyancy. 
"Does wood float?" I asked.
"No, it is too heavy," Naftali replied.
"What was Noach's teva made from?" I continued.
"Wood!" Yehuda replied.
"Saba Larry's boat isn't wood but it floats," Adina added.
"Some items and some shapes float, while others don't. If they don't float on the top of the water, where do they go?" I asked.
"They sink to the bottom! They go down down down," Elazar explained beautifully.

The students were presented with a tray of random items. In turn, each child selected an item and guessed whether or not it would float. I explained the word 'hypothesis' and that we were scientists doing research. 

Once everyone had an item we tested our hypotheses.