The most common emergency congregation of mass students in secondary and elementary schools is either in the hallways, gymnasium, or assembly halls to keep away from windows. When schools are built, they usually add reinforced concrete to those areas for extra protection. You have to keep in mind the number of students also. I grew up in small schools all of my life, so we would go into the hallway, sit on our knees, and cover our heads. In a large school like the one she's in, there isn't enough room for that many people.
What do you propose our tax money to be used when a new school is built? It's not cheap for a school to be built in the first place, but you add some kind of shelter and the citizens of the town who live there wouldn't accept the tax hike referendum. In the late 80's and early 90's, the state of Illinois was in trouble as over 50% of the schools were trying to pass a tax hike to fund the local schools. The only problem is that the citizens were broke as it is and couldn't afford another tax and most of the referendums failed.
Where do you go during a tornado drill? Since you live outside the US...are you familiar with tornado's enough to warrant a complaint? Here's a few pictures of a tornado that hit a manufacturing plant a few years ago. It was listed as a F4.
Roanoke tornado starting
Tornado hitting plant after hitting silo
Tornado view 3 miles away
What was left of the plant that got hit.
Summary of the tornado event with more pictures