Mental Blocks

Block by Block Jr. is a 3d construction puzzle based on the classic Soma Cube puzzle. Like the Soma Cube, Block by Block Jr is a great way to learn to visualize shapes in 3 dimensions — an important skill in science, math and engineering. For instance chemists visualize molecules, mathematicians visualize data, and architects visualize buildings and other structures. Solving Block by Block Jr. puzzles also develops problem solving and teamwork skills.

Every year my daughter’s elementary school stages a day of hands-on science exhibits called Discovery Day. For this year’s event I decided to build a giant 3d puzzle, inspired by giant Soma cubes other people have built out of cardboard boxes. However, when I tested the Soma cube on kids, I found it was much too hard. Adults too had trouble with it.

So I developed a simpler version of the Soma Cube, with fewer, smaller pieces, which I call Block by Block Jr. The original Soma cube has seven blocks that form a 3x3x3 cube. Each block is made of 4 cubes, like a Tetris block, except for one block that is made of 3 cubes. Altogether the blocks contain 27 cubes, and can be assembled to make a 3x3x3 cube.

Block by Block Jr has six blocks: three blocks made of 4 cubes each, and three more blocks made of 1, 2, and 3 cubes. Altogether the blocks contain 18 cubes, and can be assembled to make a 3x3x2 rectangular solid. Block by Block Jr puzzles are definitely easier than Block by Block puzzles, but the hardest ones are still quite challenging. Here are the six Block by Block Jr pieces.


For Discovery day I built three versions of the puzzle: a giant version featuring built out of 10″ cubical cardboard boxes stuck together with duct tape,


a half-sized version made of 5″ cardboard cubes,


and a small version made of 1″ wooden cubes


In all three versions of the puzzle I stuck colored dots onto the blocks to make it easier to identify which block is which.

Here are instructions for making your own set, including where to order cardboard boxes and wooden cubes.

And here are challenge sheets containing puzzles that require 2 to 6 blocks. Caution: there are answers for only the first 5 (of 10) challenge sheets.

You are welcome to make copies of this puzzle for personal use or for gifts, but please do not sell them…I’m working on turning this puzzle into a product.