Note that the basic plan for each operation is based on what students already know (putting together, taking away, sets). The only new idea is adding or removing zero, and of course the minus area. The approach is consistent with the Lab Gear activities on "Which is Greater?" and equation solving, and should precede them. It can and should be combined with other ways to work with signed numbers. For example, see these games which provide another visual approach, and involve decimal numbers.