They found resources like Khan Academy and they were able to fill in those gaps and master those concepts, and that reinforced their mindset that it wasn't fixed; that they actually were capable of learning mathematics.
Eles acharam fontes como a Khan Academy, e conseguiram preencher essas lacunas, dominar esses conceitos e isso reforçou a mentalidade deles de que aquilo não era imutável, de que eles eram capazes de aprender matemática.