As a practicing scientist, I would have to disagree that labs are not important. They are essential! I cringe when I hear of high schools that do not expose students to lab classes. Here's the catch...you can't design labs that always work. The best designed lab I ever experienced was one in which it was intentionally designed to disprove the hypothesis (this was a biology lab). Writing up a lab report about a "failed" experiment is worth its weight in gold in really driving home the lesson of what an hypothesis is and how to interpret results and draw a conclusion and write a quality discussion about it.
One thing that a lot of scientists have in common is that they are tactile or kinesthetic learners. We don't really understand something until we get our hands into it.
Labs should not just be "add chemical A to chemical B and watch the color change." There needs to be an hypothesis, predictions, experimental design, results, interpretation and conclusion. And there are experiments you can prepare that allow the students to develop the hypothesis and still do the same experiment whichever hypothesis they go with.
For example, one we did in high school chemistry (sorry, I don't remember the actual reactions anymore, but I'm sure you could look it up) was to compare brand name and generic household products for amount of active ingredient. For example, you could ask your students to develop an hypothesis regarding whether a generic brand of bleach and a name brand are the same or different in their content of sodium hypochlorite. Either way they go with it, you're going to do the same analysis of sodium hypochlorite content. Then they will either support or disprove their hypothesis and have to write up a lab report discussing that. The other good thing about this approach is that each year, the hypothesis being tested is decided upon by that class, and is not going to be the same year to year, so they can't just pass along lab reports from one class to another.
But this is a process. The first lab really might just be a gee whiz, look, we added clear chemical A to clear chemical B and the color changed from clear to pink, followed by a discussion of why properties of compounds are different from the reactants used to form them. This just gives them a chance to learn how to use the equipment, such as balances, test tubes, titration burets, being careful not to spill, etc. Then, you'll move on to some experiments where you give them the hypothesis, predictions being tested, and then they just get the results. Next step, you give them the hypothesis, but they list the predictions and are guided in designing an experiment. Last step is you let them form the hypothesis (in high school, you're going to pick experimental topics they can have opinions about...when they get to college we worry about them having to do a little more research about a subject before forming an hypothesis), predictions, etc.
Not all of your students are going to become scientists. In fact, very few will. For those who don't, the labs will just be a break from boring problems or lectures, maybe no added benefit, but no harm done either. For those who have a spark of interest in science and may become a scientist, those labs are very important. Don't underestimate simply teaching them how to use a balance to weigh chemicals, or how to read the volume of a liquid in a graduated cylinder (accounting for the meniscus). These are minor but essential skills scientists use every day. But if you take it a step further and truly teach them to understand hypothesis testing, you will likely be the teacher they come back and thank years later for hooking them on science.
