In the book roll of thunder hear my cry why did the kids get spanked at church?

In Roll of Thunder, Hear my Cry, Stacey was spanked because T.J. threw some cheat notes to him during a test. Mama was substituting, came in, and saw the cheat notes in Stacey's hands. Stacey was spanked for "cheating", when T.J. was the true culprit.