When to call 911

We know that we need to call 911 in an emergency situation.
I found this book does a very good job of teaching our little ones when exactly to call 911.
"It's time to call 911" by Smart Kids Publishing.

If you would like to know more about this serrvice go to http://en.wikipedia.org/wiki/9-1-1.

I had to educate myself before I could answer some of my daughter's smart questions and the above link was helpful.