To me, something that I learned this semester in PSY 1001 that will most likely stay with me for the next few years (and possibly the rest of my life!) is the task of consevation.
Piaget explains that children in the preoperational stage do not pass the test of conservation. Piaget's task of conservation requires children to understand that despite a transformation in the physical presentation of an amount, the amount remains the same.
Here is a video that show several great examples of tasks of conservation and how a young child executes the task and the reasoning he gives for his answers.
Watching videos like the one above never cease to amaze me. For college students like us, the idea splitting a group of coins into two equal groups and then stretching one row apart does not affect the amount of coins in the row comes very easily to us and seems like second nature, but in the eyes of a child this becomes a much different story.
Children of a young age seem to grasp onto the belief that such physical changes can change the amount of a substance. Until about age seven or so, children seem to believe that "since A is visually bigger than B, A must have more this substance!"
I for one hope that I can test this on a child I hope to have some time in the future!