Let me tell you how much I love Flickr! Several nights ago I was busy late into the night (well, midnight) exploring the site and generating all sorts of ideas for using the images on this site in my classroom.
Let's begin with the tags section of the site. I'm currently in the middle of a unit on geometry so I was interested what I might find in the architecture and buildings section. Here I found a cornucopia of photos containing parallel and perpendicular lines, geometric solids, & symmetrical buildings, all in a real-world context. An image like this one could be posted to a discussion forum or group blog to elicit discussion about symmetry.
While exploring the above tags, I came across the urban and street tags. There were photos that illustrated the above concepts. However, it wasn't until I came across a photo that took me to the squared circle group that I really got excited. Thinking of problems that related to the photos was incredibly easy. I started blogging the best of them as I went so that I wouldn't forget them (see a few below). The rest I put in my favorites. So many concepts could easily be covered through these photos--fractions, concentric circles, and more.
So I know I can take the pictures from the site and use them elsewhere, but how could I have my students actually find their own photos on the Flickr site? I thought a tag scavenger hunt might be interesting. Give the kids a concept and have them search under related tags for photos that illustrate that concept. The only problem with this activity is that some of the photos are titled with inappropriate language or have inappropriate content. A solution might be to have students do a favorites scavenger hunt. If you have a concept in mind, like parallel lines, search for photos that contain examples of parallel lines and add a ton of them to your favorites. When mixed with the other photos in this page, students will have to look closely to find the pictures that best illustrate this concept. When they have found one, have them blog it with a short description.