Activities  often involve creative construction with blocks and other construction manipulatives, with the teacher noticing, describing, and encouraging types of 3D composition that are at the next level for children (challenging, but achievable). Asking questions (What if you used the same structure in all four corners of your castle) and showing pictures of actual buildings and block buildings that illustrate that type of construct might motivate children to try that new way of composing 3D shapes. Copying each others' construction can be another helpful approach.