The making of this periscope is part of our STEM project. In order to make this project available to other teachers as well, I'd like to share this instructable.
You'll need to use a laser cutter and as material you'll need MDF 3mm and mirror plexi 3mm.
First you need to check whether you have all the parts.
Put the shown parts in the same way in front of you.
Put the sides up and with some force you'll be able to fasten these to the below part.
You press the left over rectangular part on the top.
Put the small mirror part at the end between the four holes at the sides - pay attention that the mirror side is directed to the inner side of the box !
Take the small and bigger ring.
Put the bigger ring on the top of the two rectangular stick-outs (just on top of the mirror that you have just placed).
Put the smaller ring on top of the bigger ring.
Take the remaining parts.
Put the remaining mirror between the wholes of the circles.
This new part you place between the holes.
Put you periscope at its side and put a little bit of (wood) glue at the circles (only two small dots as you can see in the picture).
Then you place the "turning" wheel on the circle - pay attention that the hole fits on the piece of mirror that still sticks out !
You repeat the previous step at the other side.
Your periscope is ready for use now !