Since someone else mentioned cover letter, I'm going to mention that your resume may seem good to you (and to colleges, apparently), but is lacking in the key elements or wording that schools may zoom in on. I've told the story before that my son graduated with a supposedly "great" cover letter and resume. He applied everywhere, to no avail. He was taking care of everything, so he didn't share the resume and cover letter with me. When nothing transpired and he was in despair, he finally shared it with me, and I was livid that a university would say that the cover letter and resume were "great", because they were far from adequate, forget about great. I'm an educator, too, and I had my resume written by a service found online. I told my son that my gift to him would be a professionally written resume and cover letter, but I needed to see and approve it, since not all writers get it right on the first try. Fortunately, after a couple of less than stellar rough drafts, his work got bumped up to a writer with more experience. The results were amazing. The next year, with the new resume and cover letter, the interviews poured in. When he finished his MEd., I once again gifted him with a new resume to play to his new strengths and skill sets. It was exceptional, and is the one he uses today. It has been modified by us when significant skills are acquired, or experience gained.
This whole experience with a university sending out students with less than professional sounding resumes left a bad taste in my mouth. Many writing services will work with you until you approve it, and have reduced fees for new grads. Some people can write their own resume, I'm sure, but in a highly competitive field, such as elementary teaching, I would insist on something that rings all the right bells and grabs attention. If you can't get the interviews, you can't get the job.