School shootings in the USA are not uncommon, although it's difficult to agree a number as the definition is unclear. For instance, firearms have been discharged in schools 17 times this year. Although 13 of those were accidental and didn't lead to any deaths, there is still the question of why there were guns in the schools, and that leaves 4 preemptive shootings in just 2 months. In fact, there have been 290 such incidents since 2013. Even one incident is too many and totally unacceptable, especially if it leaves 14 children and 3 adults dead, as it did in Florida.
America is a country that allows guns to be held by individual citizens, as stated in the Second Amendment of the Constitution passed in 1791, and that right is strongly defended by the National Rifle Association. The NRA has about 5 million members and a high income that they use to influence politicians. Rather than contribute directly to election candidates, they choose to spend a fortune on advertising and campaign tactics that persuade voters to back a candidate who supports them. Conversely, if a politician speaks out against the NRA, money will be spent to defeat them. $420 million was spent in this way in 2016 and the Republicans were the main winners.
In general, guns cannot be purchased by anyone under 21, but can be used at a younger age and there are exceptions in some States, so that a person of 14 can legally buy a gun in Missouri. Nikolas Cruz, the killer in Florida is 19 and legally possessed the guns he used. Compare that with the fact that alcohol cannot be purchased by anyone under the age of 21 in any State and it doesn't make sense.
After the Florida tragedy, some students have started to protest about the use of guns. This has resulted in a few companies breaking off their association with the NRA, but it's unlikely that it will go much further. People have protested after every mass shooting, but to no avail. The gun lobby is too powerful.
Having read Michael Wolff's book 'Fire and Fury', which describes Trump as a president unable to think for himself and being easily influenced by others, I have no doubt that the NRA has approached Trump and suggested the idea of arming teachers; it's a subject they've raised before. However, if I could speak to Trump, I would remind him that, on average, 96 people in America die of gunshot wounds every day, 7 of whom will be children, and the total number of American citizens needlessly killed by guns each year is close to 13,000. What a complete waste of life! Times have changed since 1791 and the right to carry arms in today's society is clearly wrong. Why not be a strong president and change the Second Amendment, ban gun sales to individuals and save many lives? That sounds like a simple solution to me.