Here are some of the resources I've been using for teaching kindergarten math:
1) Kumon My book of Numbers 1-30
I really like the Kumon books. They are reasonable priced and they do a great job scaffolding each skill. We had been using another book and I could barely get her to finish one page at a time. My daughter (age 4) did the first 20 pages in this Kumon book in one sitting. Then the material started getting a little more difficult and so it has been taking her longer to complete. The last several pages do get a little monotonous but I solved this problem by buying several prizes for our prize box at the 99 cent store. I told her that every time she finished a page in this book that she could put 2 marbles in a jar (the jar is about the size of a baby food jar). When the jar is full she gets to pick a prize.
2) 101 Things Every Kindergartner Should Know About Math
We are also doing this book. The math concepts and processes taught in 101 Things Every Kindergartner Should Know About Math include:
Basic math skills
Understanding number values
Addition and subtraction
I have been very pleased with this book also. The book is colorful and fun and provides additional ideas to do with manipulatives to reinforce the learning in the book. My daughter gets 1 marble to put in the jar for each page in this book since the pages are usually less time consuming than the pages she is working on in the Kumon book.
Update: My 4 year old finished this book today 2/28/11. I think the reason why she liked it so much is because it is so colorful and fun looking. Unlike the Kumon book (above) she never got to a point where she was tired of doing it. She would sit and do 6-8 pages at a time.
Check out what Mommy Maestra is doing to teach number placement with beans.