Take the situation as a challenge. Creative people often say that they work best with limited resources. I think this has something to do with 1) a necessary self-reliance that draws on personal strengths and 2) a naturally gained, full understanding of the resources that are available.
If you have a violin with just one string, you have a good chance at becoming a master on that one string. Better to be a master on one string than a novice on four.
Facilities do not make the teacher, though they certainly can make one's job easier. Technology, in particular, is a big help. But the principles of teaching are the same no matter what the facilities. Learn as much as you can about the subject matter, build relationships with students, and critically assess your methodology. And, of course, be flexible, especially if difficulties often arise with technology or other infrastructural issues. This is not, again, to downplay the importance of facilities, but we all have to do the best we can.
You use what you’ve got. You could be a teacher in the dirt, if you needed to. However, I agree with you that schools are poorly underfunded. I think the key is to make people aware. The kids and their parents see it every day, but what about the business owners and politicians? Take a video and put it on YouTube.