This study reports on the impact of a "massive, open, online course" (MOOC) designed to change students' ideas about mathematics and their own potential and improve their mathematics achievement. Many students hold damaging fixed mindsets, believing that their intelligence is unchangeable. When students shift to a growth mindset (believing that their intelligence is malleable), their achievement increases. This study of a MOOC intervention differs from previous mindset research in three ways (1) the intervention was delivered through a free online course with the advantage of being scalable nationwide (2) the intervention infused mindset messages into mathematics, specifically targeting students' beliefs about mathematics (3) the research was conducted with a teacher randomized controlled design to estimate its effects. Results show that the treatment group who took the MOOC reported more positive beliefs about math, engaged more deeply in math in class, and achieved at significantly higher levels on standardized mathematics assessments.

A wide range of evidence points to the need for students to have a growth mindset as they approach their learning, but recent critiques of mindset have highlighted the need to change teaching approaches, to transfuse mindset ideas throughout teaching. This shifts the responsibility from students themselves to teachers and schools. This paper shares a mixed methods study conducted across the US, that measured the impact of a “mathematical mindset teaching approach” shown to be effective when taught by the authors, scaled to teachers in 10 US districts. The effectiveness of this novel mathematics approach was measured using pre and post assessments during a summer intervention followed by measures of GPA change when students returned to schools. Both measures showed that a mathematical mindset approach to teaching significantly improves students’ mathematical achievement, and changes students’ beliefs about themselves and their approach to learning. Accompanying analyses of teaching and of teacher interviews give insights into the ways students change, highlighting the need to bring about shifts in students’ mindsets through a changed approach to mathematics teaching and learning.