"One of my favorite free iPad apps of 2013 is the World Wildlife Fund's Together app. That app features interactive stories about endangered species around the world. The stories show you where the animals live and the threats facing them. If you and or your students don't have iPads, you can access similar information through WWF Wildfinder."
With Classkick, students work assignments on their iPad and get instant feedback. Teachers create assignments, see all their students' work in real-time, and give LOTS of student feedback. Best of all, students can help each other anonymously (App is available in SELF-SERVICE and scoped to all iPads).