debating whether or not to take 9th grade bio over the summer. I’m already taking geometry, so I can do algebra 2 my freshman year, but is it too much? most of my grade (that’s in algebra 1) is doing geometry over the summer but only a few are doing biology. if I do biology then I’ll take chemistry my freshman year and be on track to take 2 ap science classes. obviously bio is easier than chemistry, but should I take bio now so I don’t have to do a harder class over the summer later on?
Depends on your career path. Most 9th grade Bio is nothing but vocab and memorization and serves as somewhat as an intro into AP even though AP Bio is HEAVILY reliant on the applications instead.
If the only reason you’re interested in taking 9th grade bio over the summer is so that you’ll be on track to take 2 AP science classes, you may want to consider options besides trying to complete it over the summer.
I took biology honors my freshman year, then did both AP Bio & Chemistry honors my sophomore year (I did double block AP bio in place of 2 electives), and then followed up with AP Chemistry this year. I’m a junior this year and taking AP Environmental Science next year, so I’ll graduate with 3 AP sciences and NO summer classes to have done it.
Point being, if the only reason you want to do it over the summer is to be able to take 2 science AP’s, that is not necessarily your only means of doing so. Double check with your school, but you may be able to double up on science classes in one year if you’re up to the challenge (I know for me, the biochemistry unit of AP bio last year was a struggle when I had only just gotten my start in honors chem)
my school is ridiculously overcrowded and doesn’t let us double up on math or science classes 
we can’t take honors in 9th grade either for some dumb reason
that’s too bad - if you were to take 9th grade bio over the summer, would you be taking it online?
Freshman biology is not very difficult if you’re good with vocabulary and memorization. It’s mostly just about being able to successfully learn & regurgitate facts and terms. There is very little math compared to chemistry or physics. It shouldn’t be too challenging, assuming you’re ok with the memorization aspect.
Make sure you have Biology, Chemistry, and Physics. If your school’s overcrowded, taking Bio over the summer may be a good option, as long as you can take Chemistry Honors then Physics Honors (or AP Physics 1).
However, if you sole motivation is taking 2 AP science classes, which would those be and why would you take them?