When an iPad is unresponsive (doesn't respond to touch / is frozen / acts weird), a "Hard Reset" is probably a good step.

The Hard Reset is like pulling the plug on a standard desktop computer; it forces the iPad to reset everything.

To perform the Hard Reset, press and hold both the Sleep / Wake Button (on the upper right corner) and the Home Button (the round button on the front) until the Apple Logo () appears after the device turns off.  This usually takes from 5 - 10 seconds.