Help needed with lesson ideas for third graders.

I recently found out that I will be teaching 2 classes every Thursday.

They will be still receiving instruction in the computer lab every week and they will meeting CIPA compliance while in there.  

I am in need of help with additional lessons to teach the students.

I am thinking about teaching them to code.

I am limited to a MacBook cart per class.  If I use iPads then I will have borrow them for the other teachers.  One class has 5 iPads the other class has 6 iPads.  There is one set of iPod touches that I can use but the other class will not be able to use them until the following week.  

I have a tutor that is teaching the same lesson at the exact same time that I am with another class right next door to me and if she needs my help I am supposed to be available to her.

I want to this be something fun for the students and something different. Any thoughts and suggestions would be greatly appreciated.