I placed funnels in the holes in the wood and partially filled the tub with water.
The children and grown ups loved it. Scooping up water and pouring it into the funnels over and over. The water disappeared through the funnels but there didn’t seem to be much interest in where it was going.
I saw a couple of adaptations; the first was using a chopstick to prop a smaller funnel above the larger funnel. With this structure the children could see the water run from the small to the big funnel then disappear.
The second adaptation had the funnels stacked inside each other with the chopstick coming out the bottom. This structure slowed the progress of the water through the funnels and allowed them time to see the water coming out the bottom.