Addition & subtraction strategies to solve two-digit equations using an open number line. In this lesson, students go over using addition and subtraction strategies to solve two-digit equations using ...

Students go over using number lines to solve the four equations in a fact family. In this lesson, students go over using number lines to solve the four equations in a fact family. Julia uses charts, ...

For all of the recent strides we’ve made in the math world—like a supercomputer finally solving the Sum of Three Cubes problem that puzzled mathematicians for 65 years—we’re forever crunching ...