Quick Response codes are like bar codes on steroids - depending on the characters coded, they can store between 1,000 and 7,000 characters. They can be used to engage students using their mobile devices with a camera and appropriate apps. QR hacker, QR stuff or kaywa qr codes are three sites where you can create your own QR codes. There are many free and paid apps for idevices and android phones that allow you to read these codes. Here are some ways I have used them in science with middle years students:
1. Students create a wiki page about an organ (heart, small intestine, kidneys) and then use the URL of that page to create a QR code. Attach the QR code to the body part of your 3D human body model and other students scan the code to find out information about that organ. This same strategy could be used for the common and scientific names of bones in the skeleton or common and scientific names of plants in the school garden. This blog post "Human Body Systems" describes how I used QR codes with my Year 8 Science class and "Dem Good 'Ol Bones" describes a similar task with Year 7 students.
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2. The Periodic Table of Videos (available on Flickr) allows students to scan an code and find a video about a particular element.

3. Create QR codes that give the scientific and common name for plants and trees in the school garden. You may like to provide a website (DSE or a field guide) that provides more information about that particular species. This might be part of a topic on "Classification". Laminate the codes and attach them to stakes near the plants.

4. More Maths than science.....Create a 'treasure hunt' using QR codes around your school - or better still, ask your students to create one for another class. Start in the classroom with a code that directs the participant to the next location - "The south-east corner of the stadium"; "30 metres north of the bus shelter". Students take photographs at each location to provide evidence that they have followed the directions, like "orienteching".