Sam buys a hollow, plastic rock where he plans to hide his spare key. He puts it near several other rocks by the door and calls to his two children, a $3-$year$-$old and a $6(1)/(2)-$year$-$old. He said he was gardening and found something under the rock and asks them to guess. One says a worm and the other says some ants. Then, he lifts it up and shows them that it's hollow and actually contained the house key. Then he asks where a robber, who has not been shown what is under the plastic rock, would look for the key to the house. How do you think each child would answer? Explain.