Congratulations on such great scores !

DS who is in 4th Grade tested thru Duke TIP.
His scores :
English 15
Mathematics 16
Reading 18
Science 20
It was his first time taking this test. He struggles with relatively low PS and WM so these look like very good scores for him. Unfortunately as we expected he wasn't able to finish the Math section - didn't even have time to guess all the answers. It is his strong subject and We were hoping to get him subject accelerated in math since he complains that it is too easy for him at school.
Any tips on how to improve his English and Reading scores?