I am completely new to teaching CS and binary numbers and am not understanding the Candy Shop activity. Does anyone have further instructions on how to teach this?

If we use the flippy do, we can see that we cannot represent decimal numbers. So we have to decide whether to round up or down. If the price of candy is $1.76, you can either represent it as $1 (round down) or $2 (round up). In binary this corresponds to 00000001 or 00000010. Who loses in either case? In the first case, the customer is paying less, so the shop owner is losing money. In the second case, the customer is paying more than the price, so the customer loses money. We need to add decimal numbers to our flippy do to get more precision in our numbers. The new flippy do is shown on slide 83. I hope this makes sense. The 2020-21 version of the curriculum taught this in a slighly different way. You may find it easier to teach it this way.

Thank you so much! I will try that.