Layer your QR Codes to "hide" information
Overall I would recommend this as a teaching tool. I think it would work best with a thematic unit of study. I also think it would work better with older students (though I have not tried it with younger students).
How I Use It
I have used this app as a student in a graduate course, and as a high school teacher for my own students.
When I was the students doing the scanning, I found it to be AMAZING. It was fun and engaging to go through the various levels of a photo/document. I liked the way that it incorporated what I already knew about using QR codes, which made it seem simle.
From the teacher side of things, I found it to be more difficult to use. It now has a new name. It required me to download an app to use (they have a website, but you can't fully engage everything on it). I have to watch several online tutorials prior to using it, and still had a lot of questions I had to explore prior to using it with my students. They loved it - but it was a lot of work. I would not use it frequently.
*Because I had different options for students to scan, this was a great activity for students who are kinesthetic learners.