Teacher shortage is a common concern to many Western countries (Santiago, 2002; Schleicher, 2012; Eurydice, 2002; Ingersoll, 2003).

Teacher shortage occurs in the labor market when demand exceeds supply but the operational definition varies. Some define it according to an observable quantitative measure, i.e., number of unfilled teaching positions; others by a more tacit measure, i.e., number of unqualified teachers hired to fill empty positions (Santiago, 2002, 22). These include both uncertified teachers as well as out-of-field teachers (trained to teach other school subjects or class levels).  

There are numerous factors leading to shortage both at the national (macro) and at the school (micro) level. Factors leading to shortage in the macro level are for example, natural student population growth, increased immigration, changes in national educational policy and labor agreements, greying of the workforce, and low prestige of the profession. Factors leading to shortage in the micro level are local factors causing teachers to leave a specific school such as acute discipline problems, lack of support, lack of teacher autonomy, absence of professional development activities, and scarce benefits given in a certain school (King Rice et al., 2009; Cannata, 2010). Although these latter factors do not necessarily affect the overall national balance between supply and demand, they are responsible for the imbalance at the school level.

The results of the above factors, at both levels, are high rates of turnover. Turnover is a term used to describe two types of movements. It relates both to teachers who move from one school to another, i.e. movers; and to teachers who leave the occupation altogether, i.e. leavers. (Perda, 2013). In other words, these are the transitions teachers make into, within and out of teaching (Ingersoll 2003; Ingersoll & Perda 2010). While a certain level of turnover is normal and even beneficial to the health of an organization since new employees may bring new ideas and stimulates innovations, high degrees of turnover decrease the organizational productivity and lead to increased costs. This is more acute within the educational system which relies heavily on commitment and cohesion (Ingersoll, 2001). Large turnover causes not only staffing problems but consequently also threatens the quality of teachers and pupils' performances (Levy et al., 2010; Ingersoll & May, 2013).

Determining shortage at the school level is not an easy task since school principals utilize various strategies to assure that all teaching positions are filled. These are, usually, ad-hoc solutions to school needs (Ingersoll & Perda 2010), among them using substitute teachers, increasing teaching loads of existing teachers, hiring teachers without required qualifications and certification, enlarging the number of students per class and cancelling school subjects (Ingersoll 1999). These strategies, which help principals solve the immediate quantitative shortage of teachers, create, at the same time, a hidden shortage that affects the quality of the teaching workforce (Liu et al., 2008). These solutions mask the problem of teacher shortage and lower the reliability of teacher shortage forecasts.

The purpose of the current research was to obtain estimations of teacher shortage both at the national and at the school level by taking into account the turnover phenomena of both leavers and movers, both in general and in specific school subjects. In addition, we also investigated the strategies utilized by school principals for coping with the quantitative shortage in their schools.

Cannata, Marisa. 2010. Understanding the teacher job search process: Espoused preferences and preferences in Use. Teachers College Record, 112 (12), 2889-934. EURYDICE (2002). The teaching profession in Europe: Profile, trends and concerns. Report II: Supply and Demand. Guarino, C., Santibañez, L., & Daley, G. (2006). Teacher recruitment and retention. Review of Educational Research, 72(2), 173-208. Ingersoll, Richard M. 1999. The problem of underqualified teachers in American secondary schools. Educational Researcher 28(2), 26-37. Ingersoll, R. M. (2001). Teacher turnover and teacher shortages: An organizational analysis. American Educational Research Journal, 38(3), 49-534. Ingersoll, R. M. (2003). The teacher shortage: Myth or reality? Educational Horizons, 81(3), 146-152. Ingersoll, R. M. & May, H. (2013). The magnitude, destinations and determinants of mathematics and science teachers turnover. Educational Evaluation and Policy Analysis, 34(4), 435-464. Ingersoll, R. M. & Perda, D. (2010). Is the supply of mathematics and science teachers sufficient? American Educational Research Journal, 47(3), 563-594. King Rice, J., Roellke, C., Sparks, D. and Kolbe, T. (2009). Piecing together the teacher policy landscape: A policy problem typology. The Teachers College Record 111,2, 511-46. Levy, A. J., Ellis, P., Joy, L., Jablonski, E., & Karelitz, T. M. (2010, April). The causes and costs of turnover for science and other teachers. Paper presented at the 2010 American Educational Research Association Annual Liu, E., Rosenstein, J., Swann, A., & Khalil, D. (2008). When districts encounter teacher shortage? The challenges of recruiting and retaining math teachers in urban districts. Leadership and Policy Schools, 7(3), 296-323. Perda, D. (2013). Transitions into and out of teaching: A longitudinal analysis of early career teacher turnover. Dissertation, University of Pennsylvania. Santiago, P. (2002). Teacher demand and supply: Improving teaching quality and addressing teacher shortages. OECD Education working papers, 1, OECD Publishing. Schleicher, A. (2012), Ed., Preparing Teachers and Developing School Leaders for the 21st Century: Lessons from around the World. OECD Publishing. http://dx.doi.org/10.1787/9789264xxxxxx-en