Three circles cut out of heavy paper
To teach children that it is only through Jesus Christ that we can return to live with heavenly father, our own efforts are not enough. Place two circles of card stock on the floor, far enough apart that none of the children will be able to jump from one to the other in one jump.
Explain that one circle represents us here on earth, and the other the celestial kingdom where heavenly father lives. Place a treat on the 'celestial kingdom' circle and challenge the children to jump from the 'earth' circle to the other without touching the floor, in order to gain the treat.
When they have tried unsuccessfully, place a third circle in the centre between the other two with a picture of Christ on it. Ask them to try again using the middle circle to help them make it across without touching the floor.
After they have all had a treat, explain that without Christ we can not possibly make it back to our father in heavenly no matter how hard we try. The 'jump' is just too far. We have to rely on the saving grace of Jesus Christ to get us there.