I advertised for undergraduates in my sophomore level class and at the "Women in my field" meeting. This got me two undergraduates interested, which was more than I was expecting.
I've always taken the joke about passing the grunt work one encounters down to the person on the rung below you a bit seriously. So I've always kept an eye out for possible spin off projects that require a lot of grunt work and may not be worth my time and interest at the moment. These are easily given to undergrads, and as confounding says, it allows failure to be an option. If I'm not terribly interested, then it is okay for the undergraduate to fail, or flake.I'm fortunate that my university strongly encourages students to enter research early (as soon as their first summer). I also went to a similar institution. This has it's advantages and disadvantages. The research experience is great for the students. That's beyond debate I believe. Since I'm throwing undergrads problems that are not immediate priority to me, any significant progress that the student makes will move a project from the "Probably won't work on" bin to the "Should look at seriously" bin. It is always good to have a mechanism working in that direction. By living in a culture of summer research, even young students have an idea of what a summer research experience can and/or should be. Even if the students are not the most self motivated, they have an idea of what to expect. As a result, I don't have to teach the difference between course work and research.
I was one of those students who spent each of my summers in a different lab as an undergraduate. I was very interested in the work I was doing each summer, and had every intention of continuing, but then as the school year came around, I'd get swept up by coursework and other activities, and I could never give the same type of time to my summer job. Perhaps if there was a means at my undergrad institution to continue working in the lab for more than just general credit, I would have reorganized my priorities.
Karma being what it is, I now have a student working on a project that could turn into something real, but certainly not by the end of the summer. The question is, how do I keep her? My chances of having a student like this would be much smaller if I wasn't at a school where many students participate in summer research. Also, is it fair for me to expect her to stick around when she could benefit from working with different professors in different fields. She is torn in her future academic goals, and now is the time for her to sample what the different fields she is considering looks like. Since there are lots of faculty offering these opportunities, if I were an objective advisor, I may tell her to move on next summer. I certainly gained by working in different labs.
Finally, what I'm learning is that undergraduates need to learn how to do research. This sounds self evident, but I'm learning that there is more to research than just being self motivated, knowing the material, and being able to do literature search. I'm finding myself trying to teach how form hypothesis to explore. My undergraduate is very good at understanding a task, finding relevant resources, and returning with a set of results. At which point I come up with a new set of things to try, many of which are educated guesses. It takes time for her to understand why I think these may be the right thing to do, and it is hard for her to take skill that she learned in class, and apply them to a completely different situation. I know I used to be like this once upon a time. But it's strange for me to see it from this angle.
On a related note, I'm learning how difficult it is not to do the non-gruntwork parts of the problem for her. Anything that requires thinking (as opposed to doing) I can think faster than she can. It's taking a lot of self restraint to keep from running her project in the back of my mind on the idle cycles I have while doing dishes.