When I was in school, we hardly ever did hands-on work. It was mostly read the text, answer the questions, watch some videos, maybe watch the teacher do a demo to two. Computational science would allow for some minds-on/hands-on work even if doing the actual things was prohibitively expensive. In a traditional classroom, maybe you wanted to do an experiment to see what happens to fish in an ecosystem when oxygen levels decrease below levels that can support live. This would be unethical for obvious reasons in a classroom. CS would allow you to do this without worrying about actually "killing" anything.