Introducing a Number Line
Lesson 2 of 7
Objective: SWBAT place numerals in order from least to greatest on a number line.
Rev Them Up
I am using unifix cubes to get their little brain wheels turning and thinking about math today. This activity will provide them a structure to use to observe and compare numbers. I supply my students plenty of play time with the cubes the first time I get them out each year with a new group of students, but I also provide a few minutes of "exploration" time before I begin each lesson. As I pass out the cubes I am going to make sure I give them enough cubes to build three towers, one with 2, one with 4, and one with 5. That is 11 cubes each altogether.
After a few minutes I will supply my focus signal to draw their attention to me. I use several focus signals, but today I will clap a 5 beat rhythm with my hands and they know to echo it with their hands. I chose this focus signal to get their hands off their cubes momentarily.
Ask the students to use enough cubes to build a tower of 5, then build their tower of 4, and last their tower of 2. Ask them to lay them side-by-side from shortest to tallest.
Another signal I use with my students is to place their hands on their head when they have completed a task. Check out my picture to see what the students look like during this procedure. Also, view my video of a student finishing his towers and students around him who are finished and waiting.
Now follow this line of questioning:
How many is in the shortest one?
How many is in the tallest one?
How many is in the one in the middle?
So, is 5 greater than 2? Is 4 greater than 2? Is 5 greater than 4?
What do you have that is less than 5? What do you have that is less than 4?
You are helping them build their number sense and visually see with the cubes which numbers are greatest and least. Also, by placing them from shortest to tallest, you are helping them see the numbers are increasing in quantity sequentially.
Whole Class Interaction
Students need to be able to start with any number and compare other numbers to it, then decide if they are greater or least. CCSS expects our first graders to be able to start with any number and count from that spot and to cognitively notice when numbers are missing that we can still decide what would come next. (1.NBT.A.1). Our counting system has a structure and I must teach this structure for my students to be able to recognize it and use it. (MP7). Children are usually introduced to simple counting before they enter school through interaction with family members. Once our kiddos enter Pre-K or Kindergarten, they begin more advanced counting and are taught our numbers have value and build on each other.
Now I am going to build on their knowledge of physically manipulating their number towers by using number cards with no objects to represent the numbers. Pass out the number cards and ask the students to cut them apart and throw away their trash. Make sure their supply boxes are put away and their desk is nice and neat with only the numbers in front of them. Ask them to lay them all right side up, so they can see every number. Ask them to take each number one at a time and put them in numerical order. If you use name plates, they can slide each number up to their name plate and build a number line from 1 through 12 on their name plate. Walk around and assist anyone who is having difficulty. My goal for the following activity is for my students to identify numbers in order from least to greatest, placing them in that order, and visualizing these numbers as part of an order "number line."
Now ask them to pick up their 2, 4 and 5 card. Use the following questions to lead them to place the numbers in order from least to greatest.
Which number is the least?
Which number is the greatest?
Which one is in between?
Have them lay the numbers in numerical order as they answer these questions. After the numbers are in order I will ask;
If I wanted to make a number line from 2 to 5, what is missing? What number would I need to fill in?
Now walk them through the same procedure, but use different sets of numbers.
4, 7, 12
5, 9, 10
2, 6, 9
1, 5, 11
Students have been practicing placing random numbers in order from least to greatest. I want to continue building on this foundation by having them begin to use a number line. They have developed a strong sense of numbers are greater as they count higher. The most common number line used in first grade is a horizontal number line. I begin using this type of number line for counting and identifying missing numbers, but later I use it as a tool to solve subtraction and addition equations. This type of number line helps them see that numbers increase from left to right. Be careful to not teach that this is the only type of number line because students will eventually be exposed to vertical number lines and other forms of number lines used on tools, such as thermometers. Now they will identify what numbers are missing and fill in the answer.
Make copies of the Use the Number line practice worksheet for students to practice filling in missing numbers on a number line from 1 through 12.
It would be very easy to differentiate this lesson by supplying any of your advanced students a number line that goes higher than 12. You can find many different printable worksheets here.
Watch my video of an advanced student completing his number line to 20.