Unit pricing, best buys, call it what you will, this topic is great because it is relatable, practical and prompts rich conversation. This week I started a lesson with a lower ability Year 10 class with this image: After some hesitations one student piped up: "Do 80 divided by $5.39!" I wrote on the whiteboard 80/5.39 and the students told me confidently the answer was 14 cents. Me: "How do we know this is correct? Is there a way we can check?" After some discussion we figured out we could multiply 80 by 14 cents which they told me was $11.20. Me: "Are we happy with this?" Students: "I guess." Me: "So if you take this packet of lollies to the checkout and they charge you $11.20 you are ok with that?" One Student: "You're gettting scammed!" I was amazed. The students took quite some time thinking through how the shop keeper were cheating the customer. Eventually they were convinced that maybe the maths was wrong. It was d