Toddlers show a surprising lack of knowledge about solidity when they are asked to search for a ball that rolled behind a screen and stopped at a barrier whose top was visible above the screen. They search incorrectly, failing to take into account the position of the barrier. This study examined details of this failure by simplifying the task in 2 ways: by using a search task that did not require children to understand solidity, and by using a prediction task that did not require children to conduct a search. For the prediction task, children had to predict where a ball was going to stop when a barrier intersected its trajectory. Children 2.0 and 2.5 years old were able to conduct a simple search and could predict, to some extent, where the ball was going to stop when the barrier was fully visible. Children did not show this predictive knowledge when the barrier was partially occluded by the screen. (Contains 3 footnotes, 3 tables and 6 figures.)