Read your preschooler one book each day for school. Have your child follow along as you read. When you finish, ask him questions about the book to see how much he comprehended. Encourage him to go back and look over the pictures to find the answer if he doesn't remember. This can also easily be done at the library, and parents can even take their children to the library for reading time.
Provide your child with one handwriting worksheet each day. You may want to go over all of the capital letters first and then do lowercase letters, or you may want to have your preschooler learn them both at the same time. This depends on the specific child and how quickly she learns.
Practice counting numbers and writing them for a few minutes each day. Preschoolers should be able to count up to 10. Number printables can be used as well as real objects. Preschoolers can count their stuffed animals or the cups in the cabinet.
Give your preschooler some computer time a couple of times per week. Take advantage of Sesame Street and PBS Kids' free online games for preschoolers that will reinforce what you are already teaching them.
Print out some free lapbooks from the website Homeschool Share to teach preschoolers various science and history lessons. Some can also be used with books checked out from the library.
Add lessons on shapes, colors, patterns and matching as you have time throughout the day. You can create the worksheets yourself, or use some free printables available on the Internet.