Most colleges have a job site for students. You can look here first. Also, find out if you degree requires an internship. If so, you college of science will help you with this. Talk to your advisor. LinkedIn is a good site for internships as will as many other job related sites such as Indeed. You can also look to those in your network for summer jobs related to science. If you have 60 hours of college, you can also substitute teach. I hope this helps. Good luck!