# 2.5 Addition and Subtraction to 20

This year, it is very important that students become proficient with their math facts.  Being able to quickly recall simple math facts will help students increase their math abilities in many different ways.  I would recommend purchasing addition flash cards (they can be found at dollar tree) and working with them several times a week.  At school, students will be using Math Facts in a Flash, which will allow them to practice their math facts and track their progress.

Important math concepts

The 10’s rule: when adding 10 to a one digit number, the answer is that number with a one in front of it.  For example, 10+8 = 18.

The doubles: 2+2, 3+3, 4+4, etc

The 9’s rule: any number plus nine is one less than that number plus ten.

The goal is for students to get comfortable with math facts so that they are no longer required to use fingers or drawings to solve simple math problems.

Fact Families

Knowing fact families is also important for quick recall of addition and subtraction facts.  For example, knowing 4+5=9 and the reverse 9-5=4 can help students quickly solve the math problem 5+____=9.

Homework

fact family addition and subtraction 2