QR codes can be a great and exciting way to discover new information. It is kind of magical to see what hides behind the strange little squares.
Your imagination is the only limit for wat you can do. Here are just a few examples of what you can do.
There are many ways to create QR codes. Common for all of them is that you need to store the media online and make a QR code of the link to the media.
You can store files like images or mp3's on Google Drive and create a public link or share a link on YouTube.
Cloud QR Generator makes all of this easier. You can just pick a image, record a sound, select a video from your device and the app will upload it to the cloud and create a QR code from the link.
All modern smart phones can scan QR codes with the camera. This is great to get started, but the result opens in the web browser that often contains stuff you don't want to see.
Cloud QR Scanner is a free QR reader without ads that hides as much of the distractions as possible. For instance, if you scan a QR codes with a YouTube video you will only see the video. Comments, related videos, like buttons are hidden.