Since both of those things (dropping a teacher on the school and putting a child on a collectible or mushroom) are under the player's control, we don't really consider that a glitch. There are situations where a player will want all
children to gather at the school, and dropping a teacher there will make that happen (similar to what happens with the school's drum in VV1). The player can easily wait until the child delivers the item to its destination before calling the children to the school.
We have prevented the dropping of collectibles for things that are outside the players control (celebrations, certain events, etc.).