It is a teacher's job to understand what each child needs to be challenged in the preschool classroom and adjust the lesson plans accordingly. With some of our students, we get to our wits end because they are so much more advanced that the others. Some say "it's preschool, just move them up", but the problem with that is the child is likely not advanced socially enough to move up.
But how do we help everyone? Well we add to our classroom a few more challenging activities. During a quiet time, take that under-challenged child aside and work on adding or reading. I found something, that may help in that instance: Get Ready to Read-Letter Names
and Get Ready to Read-Letter Sounds.
For the most part, they look like good tools. I haven't used it yet but I think I might look into it for my daughter.
If you have used it feel free to let me know what you thought!