Teacher:Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
Teacher: Now, understand the problem? Solve this instance: Convex lenses are thicker in the middle than at the edges so they cause rays of light to converge, or meet, at a point called focus.
Student:
Convex lenses are thicker in the middle than at the edges so they cause rays of light to converge, or meet, at a point called what?