Math Time: Tetrominoes and Area

Yesterday, we played a game called "Tetrominoes."  To begin, we had to figure out how many different ways we could connect 4 of our linking cubes being sure all would lay flat.  We discovered that there are 5 ways that we could arrange the blocks and named each configuration:

It was important the students understood that each shape was the same whether it was flipped or turned.

(Putting these together reminded me immediately of a video game I played as a child.  Surprisingly, several of the children had heard of it too.  Tetris!  (click on the word to play!) )

  

Today, I posed the question, how do we measure a rectangle?  There are several ways that we could answer this question.  Up to this point, the students would measure it by perimeter, length, or width.  Today, we introduced the concept of measuring a 2-D shape by its area.  To grasp this concept and reinforce how area is measured in square units, we covered this paper rectangle with cubes and our tetromino shapes we built the day before:

The area of the rectangle drawn on this piece of paper is 80 cubes, or 80 square units.  The students discovered that 80= 8x10, which sounds a lot like the arrays we made last unit.  I love seeing them make these connections!  Great job, third grade thinkers!!