# Number Lines

### Addition and Subtraction – see videos below

Remember number lines from elementary school?  I have recommended this to several families whose children are missing the addition strip board, the Snake Game or  addition finger charts.    Number lines can be downloaded from the internet or can be fashioned by a child by hand.
A number line is a paper or cardstock strip with a line drawn horizontally along its width.  Along this line, you make even marks, like a ruler has.  In this case, the distance between the marks isn’t important, but it should be consistent.  Mark each notch on the number line with the numerals 1-20.  In the classroom, we only go up to 18, but the number lines on the internet go up to 20 and that is what I recall from my own school days.  This number line can be portable or taped securely to the top of your child’s customary workspace.
Using the number line, one can add or subtract any of the essential combinations, from 2-20.  If one asks the question “7+5=?”, one places the left index finger on the 7 and from there, using the right hand, touches each ensuing numeral counting off the 5 which is the second numeral (addend) in our equation.  So the left finger stays put on 7 as the right touches the 8,9,10,11 and 12 while counting “one, two, three, four, five.”  The numeral that the right finger ends up on is the sum/answer to the equation.  It will be 12.
In subtraction, to find the difference/answer to the question 9-4=?, one places the right hand on the first numeral of the equation (the minuend), which is 9, and then with the left hand, counts from right to left, getting lower down the number line as one counts off the 2nd numeral, (the subtrahend), which is 4, saying “one, two, three, four”  to land on the answer/difference, which is 5.  Try it yourself with different equations, both addition and subtraction until you get the hang of it.  Then you can show how to use it.  They are useful alone or with writing materials to practice writing equations.
You can print the essential combinations (found below), cut them out and put them in a basket, box or bag.  What a fun game to reach in, choose an equation and solve!