Five-year-old Alex and his mother visited the zoo. While they were there, Alex's mother took him to see the squirrel exhibit. Alex saw many different types of squirrels, but when he saw a flying squirrel glide from one branch to the next he pointed and said, "A bird with a tail." Considering Piaget's work, Alex is demonstrating an example of __________.
1. scheme
2. accommodation
3. object permanence
4. assimilation