I think the symbolic model will just be showing the math steps:
(2) = x + 4
4 4
(6) = x
For the pictoral, you could probably use a number line with the left side of zero representing negative numbers, the right side positive.
(8)(7)(6)(5)(4)(3)(2)(1)012345
(8)(7)(6)(5)(4)(3) (2)(1) 012345 this represents (2)
(8)(7)(6)(5)(4)(3)(2)(1)0 1234 5 this represents 4
When you subtract you put the second piece (what is being subtracted) onto the LEFT side of the first piece and see where you end up
(8)(7)(6)(5)(4)(3) (2)(1) 012345
(1) (2) (3) (4)
(8)(7) (6)(5)(4)(3)(2)(1)
012345
This demonstrates, pictorally, that when you take away 4 from (2) you end up wtih (6)
Hope this helps
11/27/2012

Nicole C.