Why does Atticus ask Bob Ewell to write out his name? What does the jury see when he does this?

While
Bob Ewell is on the witness stand,asks him to write his name on a piece of paper. The reasoning
behind Atticus' request is to show the jury that Bob Ewell is left-handed. The fact that Bob is
left-handed is significant because it suggests that he may be responsible for the injuries
inflicted upon Mayella's face. A man leading predominately with his left hand would more than
likely inflict injuries to the right side of a person's face, which is exactly where Mayella's
bruises were located. Also, Tom Robinson had his left hand permanently damaged in a cotton gin
accident, rendering his left arm completely useless. Therefore, Tom Robinson would probably not
have been able to inflict damage to the right side of Mayella's face. By proving that Bob Ewell
is left-handed, Atticus implies that Bob was Mayella's attacker.