I have 20 minutes left in the day and my iPad has only 10 percent. How can I save battery power?

I'm at school, I'm in an iPad class… Help?!
My phone is writing this, I'm have to do science on my iPad in the app notability…

Читать далее: I have 20 minutes left in the day and my iPad has only 10 percent. How can I save battery power?