For many of my students who are coming up from the lower grades, they do not understand adding or subtracting numbers, especially signed integers. I'm finding that by putting them on the number line, it helps them learn how signed numbers work.
Since I've been off traveling, my students have been using hand drawn number lines. When I get back to school tomorrow, I want to introduce the idea of a variable and then give them time to finish their other assignments.
Fuel the brain has a nice interactive number line which allows you to set the beginning and ending endpoints and the distance between points be it one or five or some other number. This makes it so students can choose the part of then number line they need. The bad thing is that it does not appear to work on the iPads.
Interactive sites at weebly has a page full of number lines including one that is easy to use for adding and subtracting integers. They page has at least 9 different number lines to use but at least one is not working so I never got it up.
Helping with math has a number line generator that is easy to use without printing it off. You can set it up so the distance is counted in ones or fives and you can set it up to add numbering every 1, 5, or what you want. In addition, this website has so many more printable number lines to choose from that there is no reason the students cannot use a number line.
As part of teaching using variables, I'm going to create a number line with the variables and coefficients. I will be also teaching them that 2x is 2 times x or x + x as a way of relating this to the previous.
By using this number line, I am hoping students will see how like terms are combined. I plan to let them have two different number lines, one with the variables and one with the constants so they have a chance of seeing that the process for combining both is the same.