Now that iOS 9 is out, you may wish to take some screenshots for instructional purposes. If you do and need to move them to your Mac, it's easy. Here's how:
Press and hold the Sleep/Wake button on the top or side of your iPhone, iPad, or iPod touch
Immediately press and release the Home button.
Voila! You can find the screenshot in your Photos app.You can then send it to your Mac via the Message app, email, iCloud Photo Sharing and more.
(And if you want to take a screenshot on your Apple Watch, press and hold the side button on the smartwatch, then immediately press and release the Digital Crown.)
iOS 9 can be downloaded free via iTunes or as an over-the-air update through the Software Update function in iOS's Settings app. To install it, you'll need to be using (at least) an iPhone 4s, iPad 2, or fifth-generation iPod touch.