Modern Day Equivalent of a PDA?

I'm sixteen years old and I have ADD. I'm noticing now that I'm having a huge problem with time management, and I've been doing my best to cope with it, but it's a really big struggle for me. I do have an agenda book, but I need to write ABSOLUTELY EVERYTHING down in it or else I won't be able to remember half of the things I need to do, and the page is only so big. I know an electronic device would help so much, since I could add reminders too, but I'm not allowed to have my iPhone out at school, and my uniform doesn't have pockets anyway. The closest thing I can find is a PDA, but those are extremely outdated nowadays, since most people are using their iPhones as such. So I'm wondering if there's a modern day PDA that only has the function of a day planner with reminders, preferably cheap, that I could use during school. (This would probably mean that it can't have Internet access via a browser and it probably can't have a calculator either, but I'm not very concerned with what it can't have, since I know I could make a case for it anyway.)

An iPod Touch uses the same calendar as the iPhone…

A smartphone. Any 9 year old could of told you that.

Kon - any 9 year old could have told you that this person is looking for a device that does not have access to the internet. You just have to read the question. A smartphone is the wrong answer.

So funny because I was remembering my PDA and asked the same question, if there was a modern day equivalent that was not a smart phone. If you find anything let me know as well.