## Categorizing Numbers and Number Lines

This week my students explored how to categorize numbers. By then end of the week students were expected identify integers and rational numbers and apply them to real-world contexts. The class reviewed what and where to place numbers on a number line and how to classify them as whole, counting, integers, rational, and/or irrational numbers.  This was an introductory lesson and the term rational and irrational were new to them.  After a brief class conversation about the differences between rational and irrational numbers the class took a deeper dive into how to identify the characteristics of each classification.  The class looked at a few true/false statements:

• Is 1,000,000 a counting number?
• Is 1,000,000 an integer?
• Is every rational number in an integer?
• Is zero is a counting number?

The class went through these types of questions and were able to respond and justify their answers.  The questions started to get more challenging as students needed to circle  multiples answers.

• Circle all of the numbers that belong to each set.

Integers:   4.5       2/3     102     -6       8       0

This was more challenging and took some time to categorize each number to see if it fit accordingly.  Students were then asked to place numbers on vertical and horizontal number lines.  I was glad to see how well the students responded to the vertical number line as I don’t believe they get enough practice with those.

Students had about 20 minutes left and one project to complete.  I introduced students to a number line project.  I ended up going with Google Draw for this project because I don’t have enough access to iPads at the time and I was able to checkout a Chromebook cart for this particular lesson.  Students were given a prompt to use dice to create numbers and fractions to place on a number line.  They rolled and found their numbers.  Students used their Chrombooks to access bit.ly/mrcoaty.

Students make a copy of the Google Drawing and added their numbers to the number line.  It took some work to manage the tools involved in this platform.

I explained what each icon meant and how they could use it to make the number line their own.  It wasn’t as smooth of a transition as I thought it’d be, but students persisted and were eventually able to place the numbers they created on the number line and dragged the label to each number.  Students were then expected to take their drawing, save it as an image and place it in their individual SeeSaw account.

Not all students finished this in class and I sent it home as optional homework for students to complete.  The above example is from one student that took it home and completed it before putting it into their SeeSaw account.

Next week the class will be investigating the number line in more detail and continue to categorize numbers.

## The Real Number Line – In Practice

Image by:  Samana

A little while back I wrote a blog post about how the typical math number line needs an upgrade.  You can find that post here.  I thought and still think that the general math number line that is introduced at the elementary level needs to be enhanced.

I believe that students should encounter all types of numbers on a number line. Students should find whole numbers, decimals, square roots, fractions, percentages, mixed numbers, etc.  Of course, the concept needs to be age appropriate .  So, in my last post I wrote about how students should understand the real math number line.  In theory it sounded like an idea that could be put into practice.  I decided to find out how the theory looked in practice.  I asked students to create a math number line with multiple components. This activity fit in well with the decimal and fraction unit that I’m currently teaching.  I gave each student learning group a sheet like the one below and a specific number range (like numbers 3 – 6).

Every student worked on this project in a cooperative group. Through this experience, I believe the students had a unique opportunity to learn about the many different ways that numbers can be represented.  See below for examples.

Overall, students were engaged and thoroughly enjoyed the activity.  At the end of the project, I facilitated an informal plus/delta chart and the feedback was generally positive.   While students were in their cooperative groups I overheard them debate the differences and similarities of fractions, square roots, decimals, improper fractions, and mixed numbers on the number line.  It was a great learning experience and definitely a project I’ll put in the plan book for next year.

Disclaimer (unfortunate but necessary) : The thoughts and opinions expressed in these pages are my own, and not necessarily the opinions of my employers.

## The Real Number Line

`Image by Winnond`

Approximately two weeks have passed since the new school year has started and I’m finding that the traditional number line (that many teachers have become accustomed to) needs an upgrade.  My math students are benefiting from the number line, but true understanding of numbers doesn’t come from a number line alone.  For the past seven years I’ve used a “typical” number line from -10 to 100 in my classroom.

Don’t get me wrong … the number line is helpful in teaching many number sense concepts.  In my opinion, the number line offers students a visual/spatial representation of the number system.  I  believe many numeracy concepts are built from understanding the system of numbers.  What is often missed, or not necessarily taught, while utilizing the number line are numbers that don’t fit the category of being whole.  For example, I generally don’t see pi or irrational numbers being part of a number line.

Recently I found a “Real Number Line” poster.  I was fortunate enough to find this poster and have utilized it to teach elementary students about the number system. I think it’s important to communicate that square roots, fractions, percentages, mixed numbers, etc.  should be included on a number line.

I actually created a practical follow up activity in response to this post here.

Instead of purchasing a poster, you could have the students create their own.  A few examples are found below:

4/25/12

I believe that Wolfram Alpha does an excellent job of emphasize the importance of a number line in the answer it provides.  The answer can be represented on a number line.  See the example below.

8/14/12

I’ve been reading How the Brain Learns Mathematics by David Sousa.

David emphasis the importance of the mental number line.  All humans have number sense.  For example:  studies indicate that the brain can decide that 60 is larger than 12, but it takes the brain a longer time to distinguish that 76 is less than 79.  It seems that when the digits are closer in value the response time of the human increased.  Visualizing many different forms of number lines would be beneficial and assist in developing better number sense skills at a young age.

I thought this quote was beneficial:

“The increasing compression of numbers on our mental number line makes it more difficult to distinguish the larger of a pair of numbers as their value gets greater.  As a result the speed and accuracy with which we carry out calculations decrease as the numbers get larger”

– David Sousa