My kids and I have been going on walks a lot this summer, I love it because this is when we get to chat about anything and everything.  Today the conversation went a little like this: 
Pipps- "Mom can we paint our house Pink?" 
 Me- "well I don't know if you're Dad and little brother would like that very much."  
Pipps- "But we could paint blue strawberries on it!"  
She is definitely a bit of a girly girl, so as we were walking we came across a very rectangular rock, a rock about the size of a cell phone soooo.....
A little glitter acryllic craft paint, and some paint markers and next thing you know you're talking on a sweet cell phone/rock.
They are really happy with this right now....in about ten years probably not.  Dang!
 Other ideas I think look like fun are...

Alphabet rocks by I am momma hear me roar
Garden Markers

Prayer Rocks by Brown Paper Packages
So have fun painting rocks with your kids.

 
