I'm surprised nobody has asked what the child wants. If this is a class for something he loves, karate, art, soccer, whatever, why should he not be able to enjoy those things as a child because his parents aren't together anymore? I would have resented my dad if he refused to let me take lessons on his day because his wife and him couldn't be bothered to take me, especially when he's already working during the day and classes last what? An hour?