Grace, the “basic math” in this case is about four years beyond anything you took.Again basic math. If the vaccine is no where near 100 effective in blocking risk of infection (even if say we give you the benefit of the doubt and say fifty percent, which so far no data seems to support), by vaccinating you are exposing students to two potential myocarditis risks (one from the vaccine and one from the infection). The only way this works out to make sense is if the vaccine is good at reducing myocarditis in natural infection and the risk from vaccination is less than myocarditis risk naturally....so far the data doesn't support that....and it certainly 100 percent doesn't support that for boosters beyond the initial shot, which is why many more countries are reluctant to recommend boosters for this age group.
Also, your numbers are completely wrong on booster effectiveness against omicron. You can keep saying “40%“ or “50%”, but that doesn’t make it true. CDC is putting it at 82% or 90%. 90% is hospitalization. 82% is doctor visit. (urgent care)

Effectiveness of a Third Dose of mRNA Vaccines ...
This report describes COVID-19 vaccine effectiveness time frames among people who received their first and second doses of the vaccine series, and effectiveness of third vaccine doses during both Delta- and Omicron-predominant periods.
