The Charlotte-Mecklenburg Association of Educators staged a rally after the school board approved a plan that could lead to laying off 456 teachers and 83 assistant principals.

Ken Gjertsen, a school board member who voted against the plan, told teachers attending the rally that the board should “compose a budget that cuts spending without laying off teachers.”

That will be a neat trick, since 83% of the district budget goes toward salaries and benefits for employees, most of whom are teachers.

The district has seen booming growth in the last few years, adding a total of 20,453 students between 2001 and 2006, an increase of 19.8%. During the same period, however, the district hired an additional 2,054 teachers, an increase of 31.3%.

If you hire one new teacher for every 10 new students, you don’t need to be an economist, financial analyst or demographic prognosticator to see that when enrollment slows, or the economy tanks, or funds dry up, you are most probably going to have to let many of those teachers go. Since Charlotte-Mecklenburg was far from the only school district in the country that went on a hiring binge during the fat years, we will see similar measures taken in most districts, and similar labor actions to forestall those measures.

Because of the nature of tenure and seniority rules, virtually all of the dismissed teachers will come from that group of young people who were drawn into the profession by dire warnings of teacher shortages and pending massive retirements of veteran teachers. If all these layoffs occur (remember, all that’s happening now is notice of possible layoffs; no one has lost a job yet), what will happen when the Baby Boomer teachers all do retire? Who will heed the call then?