Thanks for the great suggestions and resources! This is exactly what I was hoping for.
A friend of mine in a CS program told me about going to a competition in another city with her CS club. As they were making plans, she realized that the faculty mentor had only booked one hotel room for the entire club. She asked "Where am I supposed to sleep?" and he looked startled. It hadn't dawned on him that he'd need a 2nd room because he now had a female in his program. (That was actually the least of her problems on that trip, as the faculty adviser didn't go with them, there was drinking, one guy harassed her, and her boyfriend--long since ex now-- was unsympathetic.)
That's a minor example, but that sort of thing adds up and feels very unwelcoming. When I was in the National Guard, for the first few years it was either just me or me and one or two other females. At our 2-week annual trainings, we had the most difficult time finding out anything, like when we were supposed to be where, which uniform, how to get supper. The guys just routinely forgot about us. My dad was the first sergeant, and I was not shy about complaining, so eventually they got a system in place, assigning a female to be present at all the staff meetings (even though she wasn't technically a squad leader), coming down hard on the squad leaders for being responsible for getting the info to ALL of their squad, and more women joined so it was harder to forget about us.
It's all little stuff, and it seems petty to complain about, but it adds up to create an unwelcoming environment. My daughter hates complaining so she puts up with stuff and then avoids going to whatever class or event that has the problem. I know she needs to learn a different way to cope, and I'm sure there will be other petty problems, but I don't want this sort of thing to be what drives her out of engineering or math.
Once she's in the field, and it's still male-dominated, maybe I'm naive, but I think these sorts of things go away at that point. Probably to be replaced by other bigger problems. But by then she's invested several years and gained assertiveness. Or maybe not and she'll resent it forever, who can tell.
2009 Trek 7.2FX WSD, brooks Champion Flyer S, commuter bike