The first thing I want to say about the matter is that regardless of how little your child may like their science classes, “I just can’t do science” is almost never the case. I think the number of students we have tutored over the years now approaches 1,500, and of that number there were exactly two who truly could not master the material. Also we had one borderline case; she wound up in medical school. Difficulty with the subject matter is one thing, because the material is meant to challenge; but inability to handle science, at least at the HS level and even for the first couple of years of a college engineering major, is not likely. You just have to know how to study so that it sinks in.
In all science classes, and this includes biology as well, understanding the lecture material is the first priority because an awful lot of the test questions come directly out of the lecture notes. So taking down everything the teacher says, even if it is not understood at the time, is crucial. Students can, and should, review it later. The textbook will reinforce the salient lecture points missed during class, but the emphasis, and time spent, should be on the lecture notes as opposed to the textbook reading. The textbook’s primary use is to reinforce what was missed or not understood during lecture.
Second, and this is more essential for chemistry and physics than for biology, students need to do LOTS of problems. In particular, within the textbook are worked example problems that show step by step procedures for doing specific types of problems. Look at those examples, cover up the solution, try to work through the problem, and compare your version with the textbook version. Pay special attention to the consistent inclusion of units (really important) through the problem; liters, atmospheres and moles should all cancel to reflect the units sought in the answer. Then at the bottom of those problems there are always a couple of similar ones, which don’t have the solutions worked out, but do have the answers. DO ALL of these, and about a half dozen or so more problems beyond those assigned for homework. Your child will be surprised at how quickly they start to understand, and do well, in their science classes!
Be sure to give us a shout if you have any questions!