It depends on where you are in the game. But I will respond according to the post from me that you mentioned.
I'm assuming you're at the point where Lisa has been to Olivia Topless twice on Friday night:
At this point in your game, there are two ways to help Lisa with homework. The first thing in conversations is that you have the chance to do Lisa's homework by mistake. Then select this option.
In the next case, Lisa tells Max that she is doing her homework. So do not stop this and choose an option that will allow her to do her homework. Do this several times. Lisa is sure to be punished at least once a week.