The Edweek numbers are doing what they were designed to do, which is mislead you and parent / grandparent. They are advocacy numbers, deliberately distorted to make things seem as bad as possible in order to drive clicks to further their political agenda. Which is exactly what's happening here!
You could read the edweek links, or the comment by jlawson, or you could do some math yourself. School shootings (in the meaningful sense, not the BS sense that edweek uses--shootings where a student is killed, which is what people really mean) are vanishingly rare in the U.S., a nation of 300,000,000 people. "Preparing" for them is the result of innumeracy, anxiety, fear-mongering, profitability of reporting on them, and lack of critical thinking skills in the U.S. population. The risk is so small that counteracting basically any other risk is a better use of resources. Teach kids about drugs. Teach them about driving safely. Teach them about how to be safe around pools, and how to swim. Teach them to eat healthy. Build them some exercise habits.
An hour invested in any of these activities is much better-spent than an hour of hand-wringing about an almost nonexistent risk of your kid being shot in school in the U.S. It's simple math.