I have to teach a series of lessons on graphs and one I have to include is Venn Diagrams. I am a little confused on what I should teach the 3rd graders about math Venn diagrams. How difficult can I make it? Also what are some good activities to do with them with Venn Diagrams? They don't really like math so I like to try to make at least one part hands on and fun.

This has some good examples: http://www.ixl.com/math/grade-3/venn-diagrams Also, try googling 'third grade venn diagram math' ...you'll get plenty of items to sift through..

We do Venn's with science facts...bats vs. birds, penguins vs. polar bears, frogs vs. toads, Stages of Matter...I throw one on the smartboard for almost every science concept we learn. I teach 6 year olds and they can do three circles (or sometimes for fun we do squares) and they can do them on their own.

You can also look at comparing numbers for multiples, comparing perimeter v. area (and throw in another circle for volume), or to compare measurement systems (customary v. metric).

And if you have attribute blocks (mine are not blocks, just two dimensional pieces) you can demonstrate easily. Some are magnetic, which helps with a white board. For example, choose say, red shapes and square shapes. Have the kids sort them into sets of reds and sets of squares. Then have them find the red squares and place them in the overlapping area. Make some work mats to go with various directions and specific pieces to go with them. If you don't have attribute blocks, you could use foam shapes or sets of geometric figures.

Also, you could use hula hoops and have the kids actually step inside them. Use hair color and length, or shirt style and color.... lots of possibilities.