
For the kids a little bit older like my 5 yr old, I just have her stand in the corner. This may sound mean at first but she doesn't mind because she understands being considerate of others in regards to privacy.
If she doesn't want to stand in the corner (which is rare) I just hand over my cell phone (Verizon LG Voyager with external touch screen and flip open full qwerty keyboard) with the calculator function open and all of a sudden they have many buttons to play with.