Should I ask for a recommendation letter from my UPenn summer course instructor?

I am taking a Introduction to International Relations course at the University of Pennsylvania this summer, and my instructor, who is a PHd candidate, kindly offered to write recommendation letters for anyone who asked. It was not a pre-college program, but instead a commuter program offered only to people who live close to UPenn for a cheaper cost.

I know it was a very short time period (5 weeks) where the instructor probably did not get to know a lot about me, but he also said that we should tell him what we want him to write about in his recommendation (pretty nice guy lol). I already have two teacher recommendations and a counselor recommendation. The reason I want this other recommendation was because in the UPenn info session, the ad rep said that they look for teachers to talk about how a student asks for help and is always intellectually curious. During this course, I asked him questions about the content after class and was pretty active in class. He was also very impressed with the progress I was making with my project, so he can probably say something about being hardworking. I doubt my other recommenders will talk about this at all because I am pretty quiet during the schoolyear. Is it too much/ unnecesary? I know adcoms hate too many recommendations and redundancy.

It sounds like you want to use him for a rec letter. If you believe that he will represent you well then go for it. That being said, it does look good to have teachers that have known you year round or even for more than one year. Those are the ones that get to know you the most and see lots of development. I would go with your gut and maybe talk to your guidance counsellor if you’re really unsure.