After watching years of Gavin and Gage attempt to climb every object and wall in our house, we finally decided to sign them up for a real rock climbing class. It also helped that Gavin was growing a bit tired of soccer and needed something else active to do. We found this climbing gym that was catered specifically to kids called ABC Kids Climbing. It also was awesome that Gavin and Gage were able to both be in separate 90 minute classes that were at the same time. Gavin started in Super Monkey's 1 which is a 5-12 year old class and Gage started in Monkeys 1 which was a 3 to 4 year old class. Above you can see Gavin starting his first day on some of the Bouldering routes in the gym.

This is Gage getting in on the fun climbing as well. In his class, one of the techniques they first use is to hide beanie babies or some other stuffed animals at increasing heights up the wall to entice the kids to go climb and get them. It worked like a charm and Gage has basically been able to comfortably climb without fear.
There is also a top-roping section of the gym. This is Gage heading out one of the routes there with his teacher (Mrs. Reilli) bole'ing him from down below.
Here is another pictures of Gavin doing some bouldering. The routes are all color coded so you are only supposed to be able to touch the holds with your route's color tape linked to it. This is a more advanced concept and often in the beginning the kids use whatever they can grab. They were hooked after the first class, and although fairly expensive, they have an instructor to about every 3-4 kids.