If you look at statistics, it’s extremely unlikely for any school to have a shooting. 99.99999% of children from ages 0 to 18 in the USA are not harmed by firearms.
So you can waste your time and sanity worrying about that or just live without fear and find what makes you happy in life. Either way you and your kids will be safe so it’s your choice to be crippled by irrational fear or not.