At home, we have one of those tear-off "bird a day" calendars.
As a challenge, we like to try to identify the bird by slowly revealing the photo from top to bottom until we've seen just enough of the bird to identify it.
This client-side single-page app does the same thing. It selects a random species from the entire catalog of the Cornell Lab of Ornithology (over 16,000 at this point) and tries to find public photos of the bird on Flickr. It provides a trivial UI that lets you "reveal" the photo a little at a time and show the answer (common name + scientific name) to confirm your guess.
The keel-billed toucan (Ramphastos sulfuratus) always comes up first because that's the bird we used to have.
Thanks to Cornell Labs/eBird API and Flickr API for making this possible, and for Netlify for hosting the app for free at birdoftheday.armandofox.com.