Abstract
This paper reports on an exploratory study investigating Indonesian elementary school leachers' mathematical knowledge for teaching (MKT) geometry to determine factors that influence this particular knowledge. A survey was administered to 167 elementary school teachers to collect data on their educational background, and an adapted version of the U.S. based MKT instrument was used to measure subjects MKT. Analyses of variances on subjects' MKT revealed significantly differences based on the number of years of teaching Experience, educational level attained, school type, and grade range taught. A multiple regression model was developed and showed that educational level, school type, grade range taught were significant predictors of elementary teachers' mathematical knowledge for teaching geometry.