My teaching style received a major revamp a few years ago when I went through Singapore Math training. Not only did the way I teach math change, but so did the way I thought about math. These principles of understanding the why in numbers does astonishing things to students mathematical minds.
One of the fundamental concepts that students in grades 2-4 must understand is that of Number Forms. Here is my 4 day standard-based unit on PowerPoint that includes songs, interactive lessons, use of manipulatives, videos... Check it out!