What was Jesus writing on the ground?

We do not know exactly what Jesus was writing on the ground, but many biblical scholars believe He was writing the law. Could it be that the onlookers began to see laws written that they were guilty of breaking? It also gives us greater understanding when we consider the ground Jesus was writing on. There is a greater case that Jesus was writing on hard stone, since they were in the temple precinct, as opposed to writing in the earth. Why would this be significant?