Agnitus is a great iPad app for students to use. It has activities in all subjects. There are also books on the app for the students to read and it gives a report card for the parents to see how the child is doing.
National geographic kids is a great resource for informational writing for the students to look at. They have a bunch of interesting articles and activities for the students to do.
Brain pop is a source for all subjects. It has short video clips that are funny and interactive for the students. There are quizzes that the students can take after watching the videos as well.