Teaching students

Suitable

Teaching educators

Suitable

The product code on most consumer items is shown using a barcode that can be used to quickly scan a product at a point of sale. It's important that this happens accurately, since customers will be unhappy if they discover they are being charged for the wrong items. There's a simple trick built into every product code that supports them working so well; it uses simple arithmetic to check the numbers, and this activity shows how it can be accessed in a way that reveals an important idea from computer science that is right under our noses!

- Read through the guide on how to deliver CS Unplugged at a distance content.
- Go through the slides and trial them with the video conference software that you are going to present with.
- If you aren’t familiar with the original unplugged activity, review the in-person version of the lesson.
- It is useful for the participants to notice how many different places they see product codes (barcodes, not QR codes) being scanned (shops, books, loyalty cards, movie tickets, package delivery service, etc).
- Have participants bring a grocery item with a barcode on it to the session if possible.
- Find your own product codes on a variety of grocery products to use during the session. You will need at least one to demonstrate with but it is good to have a couple of different ones also to give other examples to the audience.
- Practise typing product codes and doing the arithmetic using the Computer Science Field Guide interactive.
- If you are going to use the modulo 10 functionality then familiarise yourself on how to teach modulo 10. It’s actually easier to complete this activity knowing how to add using modulo 10 - and it’s fun!

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