### #Odd Numbers and Square Numbers

Odd numbers **{ 2n – 1, where n is a natural number}** are not “odd” at all. They are in fact very interesting and geometrically beautiful. One activity appropriate for students at all levels is the sum of the first M odd numbers, which is M^2. For example, the sum of the first 5 odd numbers (1, 3, 5, 7, 9) is 5^2=25. Without 3D models, one can just use a square grid and have students color the odd numbers and talk about the progression of the sums.

With 3D models, we could reach out to more students and allow them to see, feel, and play with the multiple connections between number concepts and their geometric implications and much more. There are certainly **many ways** to make a square or other shapes!

Sure, it can be proved by induction. (1) When *M =1*, Sum=1^2, meaning the sum of the first odd number is just 1. (2) Assuming the sum of the first M odd numbers is M^2, the sum of the first ( M +1 ) odd numbers is then * M^2 + 2M+1*, which can be written as *(M + 1)^2*. (3) QED. This is nice but I still like the geometric aspect of the story.

### #Among
the Files

1. A set of odd numbers (1, 3, 5, 7, 9, 11) of the same height (20mm).

2. A set of odd numbers (1, 3, 5, 7, 9, 11) of varying height (step = 5mm)

3. The odd numbers can be printed all at once or one by one.

### #Reference

Conway, J. H. & Guy, R. (1995). The book of numbers. New York, NY: Copernicus.

- 3D model format: STL

STEAM educator, learning from and working with K-12 STEAM teachers to explore new ideas of teaching and engagement. I firmly believe ART is at the core of STEM learning or all human learning! I owe my ideas and designs to the hundreds of K-12 children and teachers and university professors I have had the pleasure of working with, in multiple disciplines-- math, science,engineering language arts, social studies, early childhood education and more! All mistakes, of course, are mine! There is no warranty or liability whatsoever implied or explicit behind the designs or ideas. They are all posted for their potential educational values.

When working with children, please strictly observe all safety and health procedures! Please refer to the NSTA safety guides: http://www.nsta.org/safety/.

LGBU Contact: LGBU@SIU.EDU

## Add a comment