movie about a magic bus or car involving math and letters

An eccentric schoolteacher takes her class on wondrous educational field trips with the help of a magical school bus.

Ms. Frizzle's sister takes her class on a slew of wild science adventures in this update of the beloved animated show.

Jack and Annie are young siblings who find a magic tree house on their way home after chasing a weasel. By using the books available on the tree house, they are able to travel through time and location. The two end up with the difficult task of collecting four medallions, each one hidden in a different place and epoch, in order to help a magician named Morgan.