Math Wire is an online resource that I used when I was in a 2nd grade classroom 2 years ago and I still recommend it to teachers. It’s a one stop shop when planning a new math unit. You’ll find links to online activities, game files to print, and many activities that integrate math into other subjects. They change out the main page each month and also focus on special days and events that happen during that month. What I like best is that it is also organized according to National Math Standards, making it easy to find something for your current focus.
Math Live is a web site that 3rd-6th grade teachers should look at whenever they are starting a new unit. It’s packed with great TV like episodes in a cartoon format introducing many different math concepts. What’s great is that it introduces math concepts to show how math applies in everyday life. Give it a look and see what you think!