From my uneducated point of view Zentangles and mandalas are elaborate doodles, but to the informed they are much more than mere (or elaborate!) doodles. All I really know is that the children like coloring them. If you want to know more on the topic, you will have to do your own research. Bentley, Jake, and Viva enjoy filling the drawings with color while listening to educational talks or audio books. Activities like this can help you focus better on the talk than if you were just sitting in a chair listening.
Some of their artwork is hanging on the schoolroom wall above the chalkboard.
The owl is Bentley's. The flowers are Jake's. Viva has been crocheting lately instead of coloring.