Simple is good. When it comes to creatively engaging kids in the classroom at a young age (K-2) you don't have to think big. One of our simplest ScrapKins Recycled Art Projects still manages to be one of the favorites for younger kids. And that always surprises me.
We take a simple piece of cereal box cardboard cut it a "ScrapKins Monster" silhouette and then kids create their own "ScrapKin" Bookmark that lives inside a book. (This project can be found in our Build-It Book.) By folding down the top of the bookmark, the head hangs over the page showing the child that their ScrapKins is waiting to be let out so they can read!
The reason this is effective is connection. From years of workshops and festivals we have found when kids are given the space and permission to "personalize" or "customize" their creation by giving it a name it becomes a friend they keep. And there is nothing simpler than a piece of cardboard (ok paper is simpler.)
We made these bookmarks at a festival a few years ago and we ran out of neatly cut silhouettes and had to "Scrap-vent" new materials on the fly using whatever cardboard scraps we could find for the kids to use. There was absolutely no difference between the excitement level or connection level of kids who had created a bookmark from one of fancy silhouettes versus one quickly created from a smaller scrap of cardboard. That was a powerful lesson about simplicity.