Bob Russo is a minor character in the Sweet Valley High series. 

Bob Russo is the chemistry teacher at Sweet Valley High.  He is also one of the strictest most brilliant and most demanding teachers at the school.  He sees potential in everyone, and aims to see that they meet it. He doesn't want his students to disappoint him, or themselves, because he really did care.

Both Wakefield twins have had him for a teacher.  While Elizabeth is a good student in his class, despite the hardness of the material; Jessica has had more than her share of troubles with the class and with the teacher.

In the third SVH book, Playing with Fire, Jessica ran afoul of the Chemistry teacher when she failed two chemistry tests (both times by cheating). Because of that, Jessica had received a pile of special assignments. 

However, Bob Russo does have a pleasant side, especially when he sees a student with very high potential, such as Johanna Porter.  Johanna, the sister of Elizabeth's friend, Julie Porter, was tested and was found to be surprisingly intelligent in science and math, and was pleased that she was working hard.