Compromise projections are almost certainly the best solution for the generic elementary school world wallmap. Triple Winkel, Robinson, etc.
Mercator’s not a great wallmap for that purpose, but its preservation of angle means it’s still very good and useful for zoomable maps like Google Maps.
Gall-Peters is not actually useful in most of the ways one might want to use a world map. The people who push it do tend to have a cheap ideological axe to grind which is not something elementary school students should have to deal with.
gall-peters is great if what you want is to compare area and for some unimaginable reason also need to compare longitude
in schools you want a compromise projection, like the robinson that was in most of my classrooms growing up
the soviets came up with the best one