Bass Lessons
Yes, at Guitar Lesson Pros we even teach bass! Since the instruments are very closely related, guitar players often learn to play bass and vice-a-versa. The mindset and overall approach is quite different between the two instruments but the patterns and shapes on the fretboard are identical (minus the two high strings for bass).
When learning bass, students will focus on memorizing interval shapes, arpeggios, and scale patterns in order to create bass lines that fit within different styles of music and chord progressions. This knowledge can easily be applied to the guitar at a later time if the student would like to learn both instruments. The opposite holds true as well.