Students count base-10 blocks and write the number they represent in this unit. Students are going to:
- Count by 10s and switch to 1s.
- Describe a number using base-ten blocks.
- Match numbers and base-ten block displays.
- Assign numbers using base-ten blocks.

- What mathematical representations exist for relationships? 
- How can the study of mathematics aid in clear communication? 
- How can identifying regularity or repetition help with problem-solving efficiency? 
- How are numbers represented, compared, quantified, and modeled using mathematics? 
- What does it mean to evaluate or estimate a numerical quantity? 
- What qualifies a tool or strategy as suitable for a particular task?

- Digit: A number used to make a larger number. The digits we use to write numbers are 0, 1, 2, 3, 4, 5, 6, 7, 8, and 9. 
- Ones: The digit all the way on the right. In the number 35, the digit 5 is in the ones place. 
- Place Value: The value of the place of a digit in a number. 
- Tens: The place next to the ones place. In the number 35, the digit 3 is in the tens place.

- base-ten blocks 
- Base-Ten Block Worksheet (M-1-1-1_Base-Ten Block Worksheet and KEY) 
- base-ten matching game cards, one set for each partnership (M-1-1_Base-Ten Matching Game) 
- Base-Ten Matching Game with Three-Digit Numbers (M-1-1_Base-Ten Matching Game with Three-Digit Numbers) 

- Watch the students work through the Base-Ten Block Worksheet ( M-1-1-1_Base-Ten Block Worksheet and KEY) as they finish it. 
- Watch the students use the M-1-1_Base-Ten Matching Game to practice matching words. 
- During the section on instructional procedures, keep an eye on the students' responses.

Explicit instruction, modeling, scaffolding, and active engagement 
W: Explain to the students that because our system of writing numbers is based on grouping items by tens, it is also known as the base-ten system. Tell them that you can represent numbers with base-10 blocks. 
H: Show the blocks that are base ten. Tell the students that the purpose of these resources is to aid in their representation of numbers. 
E: Students will go from counting in tens to counting in ones. Students will write the number that each base-ten block represents after counting them. 
R: Students will be able to consider how they grasp the concept of representing two-digit numbers with base-ten blocks through the pre-, during, and post-lesson questions. 
E: Use the Base-Ten Block Worksheet and the answers to the questions to assess your knowledge of how to represent two-digit numbers with base-ten blocks throughout the lesson. 
T: The lesson can be modified by utilizing the ideas listed in the Extension section. 
O: The purpose of the lesson was to improve students' comprehension of how to represent two-digit numbers with base-ten blocks. Students count base-ten blocks and write the number they represent after moving from skip counting by 10s and switching to 1s.

Get the class to count the following as you introduce the lesson:

- "Count forward by 10 until I tell you to stop." At 120, stop the students. (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120)
- "Count forward by 10s until I tell you to stop." At 110, stop the students. (10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110)
- "Now that we are counting in 10s, I want you to start counting in 1s when I clap my hands. I'll give you an illustration. 10, 20, 30, 40, 50.” Clap hands. “51, 52, 53, 54, 55, 56.”
- "It's your turn now. Commence at 10 and count forward by 10s; however, halt and count by 1s when I clap my hands. (10, 20, 30, 40) Give a handclap. (41, 42, 43, 44, 45, 46, 47) “Stop.”
- "Count forward by 10s, but stop and count by 1s when I clap my hands." (10, 20, 30, 40, 50, 60, 70). Give a handclap. (71, 72, 73) “Stop.”
- "Count forward by 10s, but stop and count by 1s when I clap my hands." (20, 30, 40, 50) Give a handclap. (51, 52, 53, 54) “Stop.”

Give every student nine cubes and nine longs. (Students may work in pairs and share the blocks if needed.) Say, "Base-ten blocks are what these are called." Assign a cube to each student. Say, "This is a base-ten cube," while holding one up as well. "It stands for 1. We would need two cubes to create the number 2. Tell me how many cubes it would take to form the number 6." Add more single-digit numbers and repeat. Present a set of six cubes and demonstrate the counting process. "Because each cube represents one, let's count by 1s. 1, 2, 3, 4, 5, and 6" On the board, write the number 6.

Tell the students to select a long now. Say, "This is a long" and hold up another one. "What does it symbolize, in your opinion?" (That stands for 10.) "Why, in your opinion, does a long represent 10?" (There are ten cubes in it.) "True. Ten cubes make up one long. Display two longs for me now. What is the equivalent of that number?" (20) "Alright. It's the same as when we count by 10s. Now demonstrate for me how many longs we need to reach 30." Show off three longs and count them as a model. "We can count by tens since each long represents 10. 10, 20, 30." On the board, write the number 30.

"We can also construct a number by combining cubes and longs." Present six cubes and three longs. Use a base-ten block counting model. 10 -20-30-31-32-33-34-35-36. Write the number 36 on the board. Ask students to use their longs and cubes to display this number. "How many tens are there in 36?" (3) "How many ones are in 36?" (6) Continue with the digits 42 and 75. Ask students to count the 23 and 79, as well as the numbers 56, with you.

Play Count and Pass with your students. Students should work in pairs to collaborate. Assign a different amount of longs and cubes to each pair's baggie. (Label the baggies so that when all pairs are finished, the class can review the answers and refer to the baggies by their labels.) Once students have completed counting the number in their baggie, pass the baggie to the next pair. As time allows, repeat.

Distribute copies of the Base-Ten Block Worksheet (M-1-1-1_Base-Ten Block Worksheet and KEY) to every student. As you go around the classroom, observe and clarify with the students to find out which ones understand base-ten block counting and which ones require more time to learn.

Extension:

Routine: Partners play the Base-Ten Matching Game (M-1-1_Base-Ten Matching Game). You can use the links under "Related Resources" for practice and continuing education.

Small Group: Go on providing additional guidance and modeling for students who require it. Forget counting by tens, clapping, and counting by one. Furthermore, keep having the students show and count base-ten blocks.

Expansion: Use the three-digit numbers in the Base-Ten Matching Game (M-1-1_Base-Ten Matching Game with Three-Digit Numbers) between partners. You can utilize the links under Related Resources to carry out Expansion tasks.