Subject integration can be a great way to reinforce what you are learning in any class and Scratch. One important concept to keep in mind before beginning your project is initialization. Initialization refers to instructions that set values at the beginning of a program. Most sequences of instructions will have an initialization part consisting of several instructions that ensure that the sequence always stars running from the same state.
Often time it is helpful to write out your description of the actions prior to starting to program. Similar to an outline.
3rd Grade Immigration Integration:
See all of them http://scratch.mit.edu/studios/322740/
4th Grade Story Book Integration:
See them all at: http://scratch.mit.edu/studios/286096/
5th Grade Greek Myth Integration:
See all of them: http://scratch.mit.edu/studios/286843/