I stumbled across a great measurements website while preparing for my beginning of the year science unit the other day. It is called “Teaching Measures” and it has a number of helpful resources for practicing and demonstrating the basics of measurment (length, volume, and mass).
It is directed at interactive whiteboard users, but can still be used perfectly fine without one. Right now the web version is available for free, and you can download it to your computer at a cost. I’m sticking with the first option and hope it lasts.