Stair climbing can also strength knees, but only if the stair height is under 8 inches. One of my favorite workout dvds is a series called The Firm. They spend a lot of time doing tall box climb with weights where the box height is 14 inches. I never attempt to do all those sets with the 14-inch box. My knees get so sore even though I do not have any knees problem to begin with. As a modification, I used an 8-inch step instead. If an exercise is exacerbating an injury, by all means modify it!
Great article by Lee Binz. For at least the last five years or so, homeschooling has been the fad in our local homeschool community - and that always baffled me for the reasons listed on this article.I would however, consider sending my more mature high schoolers students to a college course given in the evening. In my experience, the more serious students take the evening classes, so at least that's a plus. But even that would be a last resort.