Click on the picture below for a free copy of plurals and number sense for second grade.
I read If I Were President by Catherine Stier to my students. This book does an excellent job explaining the responsibilites of the president. It is written so young students can understand the job of the president. A second grade standard is letter writing so my students had to write a letter to a friend and tell them whether they wanted to be president or not and give one reason.
Here are some simple books on American symbols with lots of great pictures and facts.
Brain Pop Jr. has a great 5 minute video that explains the U.S. Symbols that I showed my students. They also have a short video on George Washington. Below are some short YouTube videos.