Final answer:
A linear curve represents a constant rate of learning over time, while an S-shaped curve shows a gradual increase in learning.
Step-by-step explanation:
A linear curve represents a constant rate of learning over time, where the increase in learning is consistent. For example, if a student studies 1 hour per day and learns 2 new concepts each day, the linear curve would show a straight line going upwards. On the other hand, an S-shaped curve, also known as a logistic curve, shows a gradual increase in learning, with a slower rate at the beginning and end, and a faster rate in the middle. This curve represents a common pattern in many natural processes, including learning. Therefore, the performance curve that shows learning occurring equally over time is the linear curve.