Not sure if I should tell my parents that I have been researching things about sex

It's not really their business. You're young and curious, just like they were at one point. Kids shouldn't have to tell their parents every single thing. That screws up the relationship REALLY fast. You should have your own private stuff just like they do.

I am surprised you need to research! Most people your age have had several years.. say 5-6 of sex education at school now.. so few don't know most of all there is to know.. depends on how good the education is..
I think most young people turn to the net for research now.. so i'd be surprised if your parents were that surprised.. Usual advice tho is be careful where you source information as online there is a LOT of misinformation..which can lead to unrealistic expectations on you and your partner..
I ASSUME you will first and foremost take precautions against Pregnancy and STDS

Someone should have talked to you about sex before now. If your parent's haven't, they're not doing their job right. Talk to them.

If you have religious parents,don't...

you shouldn't be afraid to talk to your parents..

They may very well appreciate that you open up about that and discuss it with them. If you're 13-15 years of age then that's usually the age when one starts becoming curious about sex, if it's not always on their minds already.

Unless you feel comfortable talking to your parents about your questions or concerns, say nothing. You're naturally curious. Parents don't need to hear or know everything.

I think it depends on the research, if it's something you really need answers to and understanding then by all means chat to your mum, but if it's just being curious..nah!!

You are within 15, clear your high school first

Why would you talk to your parents about it? It should be private.

You should ask them a few simple questions at first. See how that goes, if they are open, then ask them more!

Tell them so they can help you more on this sensitive subject