Structure of Shapes

Children count the pencils drawn in a picture and the blocks in a stack. Basics deals with what is visible at a glance, while Advanced brings in the parts hidden behind others, widening the view to include blocks on lower layers and at the back.

In Advanced, counting only the blocks visible from the front and dropping those on lower layers or at the back is the reliable error. An answer smaller than the true count identifies it. With pencils, overlapping ones get read as a single object and go uncounted.

The viewpoint shifts from sorting shapes into groups to physically assembling and counting them by hand. Following on from Types of Shapes, this thread runs through the study of nets in Shapes of Boxes in grade 2 and stretches all the way to Surface Area of Solids in grade 6.