Ask HN: Abstract shapes animation sw?

In a few days I will take part in a meeting where I have to describe (in abstract terms) how a new system will work. Without giving out too many details, the idea is to manage assets by first planning what is needed (e.g.: 1200 tons of coal, depicted as a large red square) then the user will have to refine the request by breaking up the original "need bucket", for example a smaller, 100 tons square labelled "January 2015", and so on for February etc. After this, the user is supposed to contact coal suppliers and "satisfy" any outstanding need bucket with one or more contracts from suppliers... like, I dunno, green squares, labelled with the name of the supplier and the quantity. So January red square has two smaller green squares (70 tons and 30 tons) linked to it. And so on... normally I would do this all on a whiteboard and describe details and answer any questions or objections from the audience "live". I just wondered if there is a way to present this as an animation. I am sure that it can be done with Powerpoint, and I have a regularly registered copy of it... it's just that I suck at PP, and I was thinking if something closer to a "normal" drawing app would fit my own style best. Any suggestions? (I realize that it may be too late for the actual presentation, but considering my preference for exploring technical problems in a visual way, with lots of sketching and box drawing, I hope that if I find a nice tool it will be useful in the future, too).