I started working as a faculty in the Department of Mathematics of Syiah Kuala University since 2003/2004 academic year after working at Universitas Pendidikan Indonesia (UPI) Bandung for 8 years. I got my bachelor in 1993 and master's degrees in 1998, both in mathematics, from Bandung Institute of Technology. I got my second master's degree in mathematics from The University of Texas at Austin in 2009. I got my PhD in mathematics education from Texas State University in 2013. My research interests are in mathematics and statistics education especially in investigating how students learn difficult concepts in mathematics and statistics as well as how to assess students' understanding. I also have a strong interest in doing research in discrete mathematics, linear algebra, and functional analysis. I started working as a lecturer in the Department of Mathematics of Syiah Kuala University since the 2003/2004 academic year. I obtained my bachelor's and master's degrees in Mathematics and my PhD in Mathematics/Statistics Education. My research focuses on Pure Mathematics, Discrete Mathematics, Mathematics Education, and Statistics Education.