Bible Belt Balabusta has a brilliant way to help young children understand Teshuva:

"I wanted my K – 3 classes to “embody” the connection between Passover and Shavuot via the Counting of the Omer, to use their bodies to travel from Passover—where the Israelites became a Free Nation, to Shavuot—where the Israelites became a Holy Nation.
First, we crossed the Sea of Reeds and became a Free Nation. On the floor were 49 steps toward Mt. Sinai on the opposite side of the room. See Mt. Sinai up there, far away?
On step #33, we paused to shoot a Lag BaOmer arrow at a target. We kept walking on the numbers till we stood on #49 at the foot of Har Sinai (an upturned pool liner) in the shadow of a giant Ten Commandments. Each student got to “receive the Ten Commandments” at Sinai: mini versions made from chocolate. Ta da! Now, we were a Holy Nation. "
Access instructions HERE