Daycare Curriculum

What curriculum should I follow in teaching 3 preschool kids, please read on.?

I am a stay at home mother who has two kids, ages 3 and 2, and I babysit my brother's daughter who is also 2. They will be 4, 3 and 3 in August/September. They do not attend a preschool or daycare and I want to work with them like those places would.

I have bought preschool work books from walmart and need some guidance as to what is normally expected out of kids of this age. I'm looking for something like a web site that I can turn to for reference as to what should be taught each week- as if they were in a real preschool classroom. What letters do we start with, how many at a time do we do, what activities can I introduce that would tie in with the letters/numbers we are practicing etc.

I thank you in advance for you answers and suggestions!

There are a lot of good responses here. Probably enough for you to feel a bit overwhelmed. Another suggestion for a week-by-week program would be from:

http://www.letteroftheweek.com/

There are weekly lesson plans for ages baby on up.

One suggestion, when using this program with my preschoolers, I found it helpful to change some of the themes to ones that my girls were more interested in. In order to find activities and songs and such to go along with these themes, I've used the following websites (all designed for teachers of young children):

http://www.everythingpreschool.com/themes/index.htm

http://www.perpetualpreschool.com/preschool_themes/topics.html

http://www.123child.com/act/

I hope you find them as helpful as I have.