The present study aimed to examine pre-service and in-service teachers' metacognitive knowledge about the frequency, efficacy, and facility of applying different problem-solving strategies in different kind of problems. This study based on the methodology presented in the research of Antonietti, A., Ignazi, S., & Perego, P. (2000). A sample of 338 in-service teachers (172) and pre-service teachers (166) participated in the study. The results are in accordance with Antonietti, A., Ignazi, S., & Perego, P. (2000). Metacognitive knowledge about problem-solving methods.