Here are some great blogs for third grade teachers!

  Adventures of a Third Grade Teacher
  Thoughts of a Third Grade Teacher
  Third Grade Thoughts

All of these blogs are by third grade teachers and they not only share their thoughts but some of their best ideas and if they worked out well or not.

Here are some great ideas for Pinterest!
    

The first one is a way to keep a good planner, the second one is a good way to have you class make snowflakes and the third is an interactive way to have your students participate in the creation of the classroom rules.