Our preschoolers learn to read and write. We use a phonics and reading program based upon Words in Color by Caleb Gattegno. We've used this successfully for over 25 years.
The children also are introduced to numbers and simple arithmetic. It's all a very hands-on approach as it must be for very young children.
Preschoolers like science. They especially like to do their own research. We let them do this.