What's in there?

"What's in there?" asked Aden as a pulled a long clear tube out of the water table. "I don't know. Try pouring some water in there and find out." I replied. So Aden used a container to carefully pour water into the funnel. "It's water!" he observed as the water flowed through the tube and back into the water table. Isaiah had been nearby watching and approached the table, picking up the other end of the tube. What would happen if water was poured into both ends? Ask the boys to find out what the discovered.