This will give them a boost in performance for the next time they go to school. If you want your child sim to get a better grade, they can also do extra credit but that is only available after they have already completed their regular homework.
If you want your sim to finish their homework quicker, you can get an adult sim to come click on the child and choose the “Help With Homework” interaction. This means that you don’t need to wait until your first day of school to get a jump start on your education. When your sim ages from a toddler to a child their homework will automatically spawn into their inventory. The whiz kid aspiration focuses entirely on building your child’s mental skill and will give your sim the mentally gifted reward trait which will help them gain all adult mental skills faster (rocket science, logic, fishing). There are 4 aspirations for your child sims to choose from: Whiz Kid For example, if you were to choose the Whiz Kid aspiration, you may want to make your sim a genius so they can feel focused often and gain the mental skill a bit faster. You’ll also get to choose a trait to go right along with it, and I’ve always been a big fan of choosing a trait that goes along with the aspiration. When your sim ages up from a toddler to a children in the game, you’ll be given the opportunity to choose a child-specific aspiration for them to complete.