The purpose of this activity is for students to analyze a mistake in ordering numbers (MP3). When placing numbers in order from least to greatest, students can compare using their understanding of place value. However, students see that unlike comparing just two numbers, there is more to keep track of when comparing sets of numbers. Students learn that a number line provides a linear representation to help organize numbers in sequence and visualize the relative distance between numbers.

• Invite previously selected students to share using precise place value language.
• Invite a student to explain using the number line.
• “When we order numbers, we can use what we know about place value. We can also think about the counting sequence and use a number line to help us see the numbers in order.”

The purpose of this activity is for students to order numbers. Students estimate the location and label numbers on a number line, and then write them in order from least to greatest or greatest to least. For the third set of numbers, students may order the numbers using any method that makes sense to them. Students reflect on how the number line can help us organize numbers (MP5). Throughout the activity, monitor for the way students explain their reasoning based on place value and the relative position of numbers on the number line.

• “How did you decide the order of your numbers?”
• “Does your list show the numbers in order from least to greatest or greatest to least?”

• Invite previously identified students to share their reasoning.
• “How are the numbers you labeled on the number line the same as the list of numbers you wrote? How are they different?” (For least to greatest, it's the same. The difference is the number line shows the distance between each number, but the list of numbers shows them right next to each other.)