Stick an image to the wall so that it is impossible for children to reach it.
Ask the children to touch the image. They will realize that this is not possible… at least, not as they had imagined.
Discuss the fact that we, like Gideon, may not feel up to the mission to which we are called. But God calls us valiant heroes and gives us strategies to achieve what He calls us to.
Finally, return to the task at the beginning (touch the image that is placed at the top of the wall) and ask the children to find a strategy to reach it: get on a chair, climb on another child’s back, ask for the help of an adult, etc.