The importance of block play in early childhood has been well documented, with significant cognitive benefits in the areas of mathematics, literacy and science as well as social-emotional competence.   Recent studies also suggest a link between creativity and spatial reasoning during childhood.  http://www.nytimes.com/2013/07/16/us/study-finds-early-signs-of-creativity-in-adults.html?smid=tw-share&_r=0 

While children are engaged in building in the block area, they are working on numerous skills and often move through predictable stages.

Stages of Block Play

Carrying

Children carry blocks, pile, knock them down and explore cause and effect.  They enjoy picking up the blocks and exploring their shapes, but are not actually building at this stage, but rather exploring the properties of the blocks themselves.

Stacking

Children begin to stack blocks horizontally and then move to vertical stacks and rows of blocks.  Patterns are often repeated at this stage.

Bridging

At the bridging stage, children begin to leave spaces between blocks and lay another block on top to span the distance.  Structures generally become taller at this stage.

Enclosing

At this stage children begin creating enclosures with blocks.  This stage involves logic and problem solving as children plan ahead to close up spaces in their structures.

Naming

This is the stage where children begin making elaborate, decorative structures. For example, the child may incorporate a bathtub, store, farmyard and swing into the same structure. Often, children name their structures (although the names rarely define the structure’s function). Patterns emerge in children’s structures, and symmetry is more intricate.

Cooperative Building

At this stage, children work cooperatively to build a structure, deciding in advance what they will build. They build their structures to look much like what they have planned in advance. Due to the complexity of the structure and the commitment of the children, they typically want to build and play with the structure over a period of several days. While building, the children assign each other roles, and they use a variety of materials to achieve the desired effects. They will also begin dramatic play around the block structure.

One benefit that I have seen from the multi-age classroom is that children tend move more quickly into more sophisticated building patterns.  The older children model concepts for their younger classmates in the block area, moving the group as a whole towards a more collaborative, creative approach.   Careful observation of children working in the block area can give teachers great insights into the developing skills of the children working and learning through play.

Source for descriptions of each stage : MacDonald, Sharon, Block Play: The Complete Guide to Learning and Playing with Blocks, Gryphon House, 2001