I am a student in 8th grade and I do a bunch with Arduino. However, I was wondering where I would go to ask for free samples.
Samples of what?
If I were Arduino (I am not) I would reserve those free samples for known under funded schools, Third world learning projects and some for those who give freely of time and effort in the support platforms.
I can think of thousands of places to distribute any freebies.
Excluding myself from that with regards this post.
Bonus points for the cheek in trying though.
I wonder if Microchip would give out free samples of the microprocessor chips? I think some of the manufacturers do.
…R
It would be nice to get some free burgers from A&W, maybe Root beer too 
Microchip (also TI) has a very generous free-sample program for chips, but I think they stopped sending samples to people with "commodity" email addresses (scammer@yahoo.com, reseller@hotmail.com, etc.
(too many eBay sales were starting to look like people who got free samples were reselling them. 
)
Schools an corporate email addresses are still good. If you're an 8th grader, your best bet might be to enlist the aid of a sympathetic teacher or parent. (back when I was in high school, I had a friend whose dad worked for National Semiconductor, and could occasionally get free samples. It probably wasn't as impressive as I thought it was at the time.)
I don't know of any "normal" source of free "board level" products. (Well, trade shows and the the occasional "free training seminar", but those aren't very accessible.) If you have a local sales office for Microchip or TI or one of their distributors, they might be willing to give free things to a school. (heh. Just a few months ago I personally sent a bunch of parts, a few Nano Clones, and I think a couple of Atmel Xplained Mini boards to a school's Electronics Club. (A school where my daughter teaches...))
OTOH, there are a lot more sources of "readily available, cheap-as-a-meal-at-mcdonalds" chips and boards than there used to be, so I'm not sure that free is as important as it used to be. I mean, an ATSAMD21 or ATmega4809 Curiosity Nano is $15 from any number of places. Occasional "free shipping", but even without that, the old "$100 minimum order, $20 handling charge" is no longer a thing...
Free? You can get these controllers for dirt cheap on Ebay. You have to wait for shipping but you can easily get Nano's for $3 or less.