Whether his teacher’s advice is a good or bad idea depends on his calculus needs for his college and major:
- Bad idea if he will need regular calculus (major in engineering, CS, physics, chemistry, math, statistics, pre-PhD economics, maybe biology), since skipping math for a year and then diving into college-pace calculus 1 in college is likely to be a harder path than calculus AB in high school.
- Uncertain if he will need calculus-for-business-majors (major in business or economics, maybe biology).
- Reasonable idea if he will not need calculus (major in social sciences other than economics, humanities, or arts; and calculus is not a general education requirement at the college).