Stack It Up
Students will be able to compare two two-digit numbers.
Introduction (5 minutes)
- Call students together.
- Ask students to think about a time they have needed to compare two things. If students need help coming up with a time, possible suggestions are choosing which piece of cake was bigger or picking the bouncier ball.
- As students think about these experiences, remind them that in these situations, they were considering which item was bigger or greater in some way.
- Explain to students that today they will be determining which number is greater.
Explicit Instruction/Teacher Modeling (5 minutes)
- Have students choose two numbers less than one hundred to compare. Write these two numbers on the board.
- Show students the tens sticks and the ones unit blocks. Demonstrate how to build a number using them. It may be useful to actually show the way that ten one unit blocks equals the ten stick.
- Explain to students that two-digit numbers have a number in the tens place and a number in the ones place. Using the example numbers, point out the numbers in the tens and ones places. Show students that they need the same number of tens sticks as the number in the tens place and the same number of one unit blocks as the number in the ones place. Build the example numbers out of blocks.
- Using the blocks, have students determine which number is larger.
- Remind students that a number can be greater than, less than, or equal to another number. Tell students the equal to (=) sign is used to show two numbers are equal. The greater than (>) and less than (<) signs look like an alligator’s mouth. The mouth wants to eat the bigger number, so it is always open towards the bigger number. Using these signs, write the appropriate symbol between the example numbers.
Guided Practice/Interactive Modeling (5 minutes)
- Repeat this process a few more times with students taking a more active role in building the numbers, determining which number is greater, and writing the appropriate equation.
- Once students seem to understand this process, tell students that they can compare numbers without using the unit blocks.
- Have students think about which is greater, the tens stick or the ones unit blocks. Once students realize that the tens units are worth more, explain that students can just look to the tens unit. If a two-digit number has a higher tens digit number, it will be greater.
- Tell students that if both numbers have the same tens digit number, students should look to the ones digit. The number with the larger ones digit will be greater. If the tens and ones digits are both equal in a two-digit number, the two numbers are equal. Demonstrate this with a few different number combinations.
- Ask if students have any questions. Send students back to their seats to work with a partner. One partner should choose 2 two-digit numbers. The other partner should record the numbers, determine which number is greater, and write the appropriate equation. Students should go back and forth making sure to record their work. Whether or not students may use unit blocks is at your discretion.
Independent Working Time (10 minutes)
- While students are working, any adults in the room should be circulating, correcting misconceptions, and answering any questions. It can be helpful to set a calming atmosphere through soft music.
- Make sure to leave any examples from the class discussion posted prominently where students can refer to them as they work.
- Enrichment: To add a greater challenge, decimals and numbers with place values in the hundreds and higher can be included.
- Support: For students who need a little extra assistance, choosing numbers ahead of time and having both partners work together to figure out the answer can provide more scaffolding. Giving students number lines or hundreds charts as another visual representation to go along with the units blocks can also be helpful.
Assessment (5 minutes)
- Whether or not students have met the learning objective can be assessed based on their work during the independent work time. Student work should demonstrate a mastery of greater than (>), less than (<), and equal to (=). Student contributions and performance in class discussions can also be considered to determine whether or not a student understands comparisons.
- As an additional assessment tool, students can be assigned more comparisons for homework. These can be done with or without unit blocks, since students should understand after the lesson that they should look to the tens place value first and then the ones place value.
Review and Closing (5 minutes)
- Call students back together.
- Ask students to share about their experiences with comparing numbers. Did anything surprise them? Did they ever confuse the tens and ones digits?
- Remind students that the greater than (>) and less than (<) signs look like an alligator’s mouth. The mouth wants to eat the bigger number, so it always is open on the side of the bigger number. If the two number are equal, the mouth doesn’t know which side to eat, so it becomes an equal sign (=).
- Encourage students to compare by looking at the tens values first. If the tens values are the same, then they should look at the ones to determine which number is greater or if the numbers are equal.