Leni doesn't do well in school- when she handed Lincoln his homework, Lincoln said "YOU did my homework?" And then Lori said "I did your homework" so I assume Lori does well in school.
In the dinner scene, the mom asked how Lynn did on her test, and Lynn said "good mom, I think I really nailed those integers." So she probably is struggling in school, but is bringing her grades up.
And everyone knows Lisa is a prodigy and graduated as a PHD already
Lincoln is the only one who we know his teacher and classmates. His teacher seems to like him enough to let him take care of the spider. So I assume he does well in school.