A note about dihedral on this series: The original "ragwing"
Cessna 170 had no dihedral - nor did the 2-place 140 that preceded it. The first metal-wing-skin model, the 170A, also had no dihedral.
But the 170B - which introduced the Fowler "barn door" flaps - also introduced the dihedral seen on all subsequent 172 models. (It
may be that it was the flaps that led Cessna to add dihedral, but that's speculation on my part.)
A personal note as an old CFI: If a student receives his initial training in a 172, he is likely to be a bit spoiled by the excellent stability of the ship, and may have a bit of trouble when first flying the 150/152; overcontrolling can be an issue. Conversely, if he starts in a 152, he'll have less problem transitioning to the 172.