In this video you'll see how students can use this Integer Operations Manipulative to add and subtract integers. You'll see how the tool can be used to find -5 + 12 and 3 - 8.
I created this manipulative for my graduate thesis and tested it out with my own students. My students were solving advanced equations wrong, not because they didn't know the algebra but because they couldn't combine integers in the very last steps. Even in 11th grade when students "should" know how to add with negative numbers, student errors dropped by 62% after using this tool.
Link to tool: Integer Operations Manipulative
I like to laminate the manipulative so that students can use a dry erase marker on it. You can read more about this tool in the blog post Integer Operations with a Flexible Number Line