I bet this topic has been talked about many many times, but I’m 16 years old right now. and I have jumpers knee in my left knee, I’m taking glucosamine right now and it helps alot, been taking it easy for about a month and a half, but it will flare up again whenever I jump off my left knee a few times, I need more recovery time?
I been doin R.I.C.E. too but its just not workin. 
You have to do a lot more than that to help your jumpers knee (aka patellar tendonitis). Stretch the rectus femoris and i.t. band, as well as the quadricep and hip flexor. You’ll also need to strengthen your knee (especially the VMO).
Ok what is a rectus femoris, and how do I stretch it.
and whats a VMO, I’m a noob 
Jason1234, rectus femoris runs from the nearly the top of your pelvis
(the boney front part of your pelvis) to the bump at the top of your shin bone. Search the web for a picture of a quad stretch. Most importantly to also lengthen your hip flexors you must keep the pelvis posterior rotated
(shorten the distance between your sternum and pubic bone). You might have learned where that is by now. In Health class of course!
Keep your butt muscles tight on the side you are stetching and hold the stretch for at least 3 minutes. There are subtle changes you can make to further enhance the stretch and a partner stretch, but don’t worry about them right now. VMO is an abbreviation for vastus medialis oblique. It’s the teardrop shaped muscle you see on the inside of your knee next to your kneecap when you extend your lower leg and “make a muscle”.
Also, are you playing basketball? Fill us in on training and game schedule, trauma to the knee if any, weight training, plyos, etc…
Who looked at your knee? Sixteen y.o. could also be Osgood-Schlatters.
Jason,
It would be a good idea to get it checked out. Can you describe what you mean by taking it easy? for example, does that mean you are taking more rest days? reducing the volume of training? You may be doing things unintentionally that are not allowing your knee to recover.
I had jumper’s knee. Stretching didn’t work. I started light with deep squats and that fixed the problem after 3 months. I’d imagine step ups or split squats might work as well.
I play alot of baskeball, and I play football and track I’m 6’1 210 pounds,not fat either.
basketball shooting guard/smal forward
football runnin back
I lift weights obviously, I’ve done plyos alot last year, but havnt really done it in a while.
Didnt play basketball this year cause stupid coach say I don’t play defense or hustle. But my knee got bad over the summer, cause I was always jumpin. I hurt it a bit at our school dunk contests, we had 3 of them last year.
taking it easy, havnt really anything for a while, not jumping, I’ll go outside and shoot the ball around and thats about it. Message my knee, and taking glucosamine, just been chillin so my knee can get better.