Adding a one-digit number and a two-digit number Adding two two-digit numbers Subtracting two digits Activity 1 Activity 2 Adding a one-digit number and a two-digit number To add a one-digit number to ...

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

Column subtraction is a way of subtracting larger numbers. It is called column subtraction, because you write one number underneath the other, using place value to sort the tens and ones in separate ...

Karen C. Fuson, Diana Wearne, James C. Hiebert, Hanlie G. Murray, Pieter G. Human, Alwyn I. Olivier, Thomas P. Carpenter and Elizabeth Fennema Researchers from 4 projects with a problem-solving ...