The Solution!

I know this doesn't really seem like a super relevant thing but I feel pleased that my idea worked so I am sharing it and then moving on, and next time I shall actually talk a bit about the children and their maths! I decided to use the little whiteboards (of which I seem to have about a million floating around the room) and groups were asked to record their problem solving on the whiteboards with felt tip pens (yes, just plain old felts - whiteboard markers are expensive and they always get ruined). Groups put the question at the top of the board. They spend about 5 minutes working through the problem in silence, then share how they are going and what strategies they are using. We are using the "talk moves" in groups too. Then we get together as a class and share strategies and discuss. And then... I take photos of the whiteboards, print them out 4 to a page, cut them out and glue them into each group's scrapbook. And it works because there is room for me to comment, room for them to write ideas for next time, and I can see exactly who is doing what.
And that is how I solved the A3 paper problem!

And for those of you who wondered about the felt tip pen ... hand sanitizer takes it off beautifully, a lesson learned when grandson decorated the walls with pen. Hand sanitizer seems to work for many things - ballpoint, felt, even vivid on some surfaces :)