Thank you for the great information. The venn diagram would be a great way from children to identify similarities and differences. I am wanting to integrate more technology into the picture of similarities and differences. Are you aware of any type of computer software that is availabe to do venn diagrams easily?
Bridget, This site was on my diigo 2.0 email this morning. http://sites.google.com/site/uteachwithtechnology/google-templates
Down toward the bottom, are compare contrast templates the kids can use on Google Docs. You and the kids would need accounts but they are free.