This is a project for our son's pre-K teacher. I had built about a dozen of these when our youngest was in elementary school (all the kindergarten, first, & second grade teacher's), but haven't made one in about 10 years. Now the lastest addition to the family is in school. The joints are mortise & tenon and the shelf is mounted using barrel bolt latches on its four corners. Additionally there are holes on the inside edge of the back (side with the horizontal steel rods) that allows the shelf to be stored when the easel is folded. The chains on the sides are safety features to prevent the legs from going flat when the shelf is removed. Previous designs used vinyl-coated wire rack for the shelf. This time I built an all wood rack and also was able to add slide-in storage bins underneath. It will also have hooks for a large flip chart which is what it is mostly intended for. CLICK ON PICTURES FOR A BETTER VIEW; THE THUMBNAILS GIVE IT A SQUASHED APPEARANCE.