I made some screen casts involving the partial sums and difference method with whole numbers and decimals if you need help understanding what your kids are doing. This is my first time trying this out, so it's not perfect, but it should help. Feel free to email me if you need any help!
Partial Different Method with Decimals didn't work, so I will work on this on Monday.
goo.gl/jmeJVq: Partial Difference Method with Whole Numbers
goo.gl/w7xj6U: Partial Sum Method with Whole Numbers