Tammy Worcester has a great explanation of the site:
This site works great on the iPads as well, and it's even easier to save the picture. Just take a screen shot by pressing the power button and the home button at the same time. The picture will be saved to your photo album. Make sure you scroll down to the bottom of the webpage for a few ideas on how you could incorporate it into your curriculum.
Here's Tonya Dean's example using the concept of division and/or fractions. It took her less than 5 minutes to do this! The picture of the text could then be put up on your website, wiki or a blog.