Encouraging Students to Persist When Working on Challenging Tasks: Some Insights from Teachers.

In a grade 9 (ages 14-15) introductory algebra lesson, the class is exploring how the m and b in the equation y = mx + b are related to the graph of a linear function. During a class discussion about these relationships, a student asks if it is possible for the graph to have 'two dots on the y-axis' - that is, whether is it possible for the linear function to have more than one y-intercept.