An "engineering pad" of paper. Basically grid paper with fine gradations. I recommend metric (!) because I think metric is best. :-)
A great calculator (or calculator app for a smartphone.) Be aware of your school's policies around calculators and phones during classes, tests and exams. I'm old enough that I used the HP28C calculator in university. A few years later fellow students were using the HP41C. I prefer HP calculators (or at least I did prefer them) because of RPN -- a method of inputing numbers and operators that makes more intuitive sense after you get used to it. Example: instead of typing "5" "+" "5" "=" you would press "5" "enter" "5" "+". I realize that doesn't make a lot of sense off the bat but when you are deep into calculations with order of operations playing a large role it starts to make a lot more sense.
Bring your curious mind, be open to learning, stay calm (some stuff is really challenging!) and your best teamwork skills.
Oh yeah, and get really good with a spreadsheet program (Google Sheets, Excel, Numbers, whatever.) You'll be using that a lot. And learn the non-standard types of charts and graphs. Scatter plot, dual y axes, etc. There's lots more in there than simple business charts.