comparing 2-digit numbers
First graders learn about comparing 2 digit numbers based on the meanings of tens and ones. Using a concrete-representative-abstract approach will ensure that all of your students are successful in this skill!
The 5 examples listed are certainly not an exhaustive list of tools and lessons that could be used to teach this skill.
They are rather a sample progression from hands-on to abstract thinking!
Which step represents your students’ current level of understanding?
Linking cubes are a groupable model. This means that your students can physically put ten ones together to create a ten. This is where you want to start when comparing 2 digit numbers.
When comparing numbers you are introducing a convention. The < and > symbols have meaning and language behind them!
Whether you choose to introduce these symbols alongside a fun concept such as the alligator mouth, be sure that, at the forefront, students are always using the language of “less than” and “greater than” and that students are writing < or >… not an alligator mouth with teeth!
Begin by asking your students to build two 2 digit numbers and to compare with the < or > symbol. Ask your students to read the full statement aloud – language is the name of the game with this skill!
You want to be sure your students are comfortable with the skill of comparing 2 digit numbers, not the skill of comparing numbers built with linking cubes.
Using a new tool such as base ten blocks can help to be sure your students are generalizing this skill and the patterns they observe.
Ask your students to build 2 two digit numbers using base ten blocks. Building their models directly on a white board allows your students to write the < or > between their two models.
Again, ask your students to read the statement aloud! You can also ask your students to rewrite the statement using numbers and symbols as well.
To support your students in comparing 2 digit numbers without math tools, add in lessons where students move from hands-on tools to representative drawings.
Build and draw directly alongside one another so your students can clearly see the connection between hands-on tools and representational drawings.
Want to increase engagement? Add in a story context! Use your students’ names and their interests as you present two numbers and ask students to compare first with place value drawings and next with hands-on tools to check their work and confirm their thinking.
As always- be sure your students are using the language of “less than” and “greater than” as they are comparing!
Supporting your students to compare two digit numbers mentally means your students need to be thinking about the number of tens and ones in a given number.
A place value chart can help to bring tens and ones to the forefront of your students awareness.
Ask your students to compare numbers in the context of a math story. For example: Julie ordered 4 boxes of ten cookies and 3 individual cookies. Gemma ordered 2 boxes of cookies with 9 individual cookies. How many cookies did each girl order? Who ordered more? How do you know?
Ask your students to first use a place value chart to support their thinking. Next, confirm your students’ thinking using place value drawings or a hands-on tool.
If your ultimate goal is for your students to be able to compare 2 digit numbers both in isolation and in context without the support of any outside aides, it is important to practice this skill as well!
Make practice fun by turning into into a game! Roll two dice and ask your students “What is the largest number you could make with the digits ___ and ___?” Repeat and ask your students to compare the two resulting numbers as well.
Students can even go “head to head” rolling dice and putting their largest numbers up against one another.
Continue to require and expect that students use math language and full statements using the words “less than” and “greater than” when comparing.