4th grade teacher bullying my child?

You do have some genuine complaints here except one thing - the teacher could not have marked him absent while she was on leave since she was not there to mark him absent. When a teacher is gone the sub takes roll and if it is a long term sub they may even be the one responsible for grades. The sub really did screw up, not her. That being said, you do have some complaints but sadly you do not have proof that your son isn't goofing off in cl. My sister had a similar problem and she began "volunteering" in her sons clroom. She would show up after getting a p from the office and help students in cl. She found out that 1. her son was kind of a goof off so he was not as innocent as she believed but this was largely because he did not know what to do and 2. she learned how she could help her son since she knew what his work was and 3. since the teacher knew she could pop in at any moment she was a lot more conscientious of how she treated my nephew. So my advice would be to get involved in your child's clroom. It will let you know what is going on and it will help you be there to stop any injustices.