Final answer:
The measure of JL in triangle JKL is 56 units, as it is twice the length of FG, which is a midpoint segment.
Step-by-step explanation:
The student's question about the midpoints of a triangle implies a relationship of proportions in geometry. Specifically, the length of the line segment JL in a triangle JKL can be determined with the information provided about its corresponding segment FG, which is formed by the midpoints F, G, and H.
In a triangle, the segment connecting the midpoints of two sides is parallel to the third side and is exactly half the length of that side. Given that FG is 28 units long, the measure of JL as a whole would actually be double the length of FG since FG is a midpoint segment, or 56 units long.