One of the easiest ways to keep track of your iPad is to keep it somewhere that only you can easily find it, like a special bag. If the iPad is yours, perhaps you’d be able to put a sticker or label with your name on it (suggestion not highly recommended for school iPads). Say both options fail you. If so, go to settings: general, pass code lock, and set your lock to a password only known to you. Then create a picture for a wallpaper with your name on it and set it as your locked page.