2's Complement

I have only rated this 3 stars because I feel like I am missing some information that would make this resource more useful - is there for example a lesson plan that goes with it? Or a project?I was initially attracted by the Amazon drone eg, but I had expected it to be developed a bit further than what I could see in the preview. I'd really appreciate knowing how you used that analogy to explain why we need 2s complement. Also - you have spelled complement incorrectly (as compliment) - I'm guessing it was the result of an overly helpful spell-checker :-). Since it's PDFs and I can't edit it, it would be great if you could post a version with the correct spelling. Thanks.