Two of the children have planned their next 'going out' to shop for supplies to make biscuits for class snack. They have chosen the recipe, worked out what ingredients we have and therefore what we need and discovered that out of date ingredients don't throw themselves out on their own. It's taken a couple of attempts due to student sickness but a shopping date materialised and a cooking session planned for the day before the start of half-term. So we'd have biscuits but no one to eat them. Compromise reached after negotiation 1 - shopping now in preparation for cooking after the break.
The girls estimated what money they needed for this trip and it realistically came to £8.50. I can buy a packet of biscuits for 45p. Negotiation 2.
But that wasn't really the point. Both facts are 'true' - 45p for a packet of biscuits, £8.50 to make our own. We used this to discuss using information to support your point of view, sources of information, checking facts.
We duly got to the shops to find that one of the girls had left her backpack at school with the money in it, so we turned round and goodnaturedly started our walk back. On putting her hand in her pocket, she found the purse! So we backtracked, shopped and the girls worked out how to share the load.
The shopping list generated 3 different maths problems - estimated costs, actual costs of the shop and actual cost of the recipe (ie you have to buy 6 eggs in order to use 1).
Negotiation 3 - why it's good for them to still make the biscuits - and I heartily agreed!