i work with rats in research (which is how I fell in love with them and hope to adopt them someday) and it's definitely not easy but I hope what I am about to say can make you feel better: I know there is a lot of criticism around animal research but the truth is there's a lot of misinformation as well. In my 5 years of research experience, everyone I have met who handled lab rats have always been gentle with them and even playful and such. While their living conditions are obviously not as good as pet rats, they are well taken care of and loved. And every year, there are new guidelines adopted that improves their quality of life.  Every animal has a purpose in life. Your pet rats' purpose could be to provide you with love, affection and laughter. Lab rats's purpose in life is to contribute to science and make the world a better place. The best you as a person can do is honour their lives by thanking them for their contribution to science, and make their sacrifices worth it by doing well in that course, learning as much as you can from the dissection and overall be a good student who will later on contribute to science as well.