The purpose of this optional activity is for students to count groups of up to 20 images presented in lines and arrays and on 10-frames. This activity is optional because it is an opportunity for extra practice keeping track of and accurately counting groups of up to 20 images that not all students may need. Based on formative assessment data and observation from previous lessons, this activity will be helpful for students who count some images more than one time or do not count some images. The purpose of the Activity Synthesis is to highlight that the order that the images are counted does not affect the number of images.

• Display the image of triangles.
• Invite a student who counted each row to share how they counted.
• Invite a student who counted each column to share how they counted.
• “¿En qué se parecen la manera en la que _____ contó y la manera en la que _____ lo hizo? ¿En qué son diferentes?” // “What was the same about how _____ and _____ counted? What was different?” (They both figured out that there are 16 triangles. They both counted all of the triangles. _____ counted across. _____ counted down.)
• “Podemos empezar a contar en lugares diferentes o hacerlo en un orden diferente, siempre y cuando contemos cada figura una vez” // “We can start in different places or count in a different order, as long as we count each shape 1 time.”

The purpose of this activity is for students to count groups of up to 20 images that are arranged in a circle, in any way that makes sense to them. Counting images arranged in a circle can be more difficult because there are not clear places to start and end when counting. Students may use different approaches for keeping track of the images that have been counted.

Monitor for and select students with the following approaches for counting the circle of hexagons to share in the Synthesis:

• Color or cross out each hexagon as it is counted.
• Place an object on top of each hexagon as it is counted.
• Mark the first hexagon that is counted, touch each hexagon as it is counted.

When sequencing student approaches, consider inviting students to share from the most common approach to the least common approach used during the activity. This sequence will help students see a range of ways to keep track of counting when images are in a circle. Aim to elicit both key mathematical ideas and a variety of student voices, especially students who haven't shared recently.

• Invite previously selected students to share in order from the most common approach to the least common approach. Record or display their work for all to see.
• Connect students’ approaches by asking:
  • “¿En qué se parecen las formas en las que averiguaron cuántos hexágonos había en el círculo?” // “What is the same about the ways they figured out how many hexagons were in the circle?” (They counted all of the hexagons and got 19 hexagons.)
  • “¿En qué son diferentes las formas en las que averiguaron cuántos hexágonos había en el círculo?” // “What is different about the ways they figured out how many hexagons were in the circle?” (They kept track of the shapes they counted in different ways. The first person colored in all the hexagons. The next person put cubes on the hexagons as they counted them. The last person marked the hexagon they started with and counted the rest with their finger.)
• Connect students’ approaches to the learning goal by asking:
  • “¿Cómo les ayuda tachar cada figura a saber qué figuras ya contaron?” // “How does crossing out each shape help you keep track of the shapes you have counted?” (When all of the shapes are crossed out, I know that I have counted all of the shapes 1 time.)
  • “¿Cómo les ayuda poner un cubo sobre cada figura a saber qué figuras ya contaron?” // “How does putting a cube on top of each shape help you keep track of the shapes you have counted?” (I know that I’ve already counted the shapes with a cube on top. When all of the shapes have a cube on top, I know that I’ve counted all of the shapes 1 time.)
  • “¿Cómo les ayuda marcar la figura que contaron primero a saber qué figuras ya contaron?” // “How does marking the shape you counted first help you keep track of the shapes you have counted?” (If I know which shape I counted first, I can stop counting right before I touch it again.)

The purpose of this activity is for students to learn Stage 2 of the Find the Pair center. Students practice finding the number that makes 10 when added to a given number. Each student starts with a hand of 5 cards. Students take turns asking their partner for a card that goes with one of their cards to make 10. When students receive a match, they put down the pair of cards and write an expression. Students draw a new card when they do not receive a match. Students continue playing until one player runs out of cards. The player with the most pairs wins. Students may use two-color counters and a 10-frame or their fingers to help them determine the number needed to make 10.

After students participate in the Find a Pair center, they have a choice of previously introduced stages of these centers:

• Find the Value of Expressions
• Make or Break Apart Numbers
• Bingo

Students will continue to choose from these centers in upcoming lessons. Keep the materials from each center organized to use each day.

• “Mientras jugaban ‘Encuentra la pareja’, ¿cómo averiguaron qué número necesitaban para formar 10?” // “As you played Find the Pair, how did you figure out what number you needed to make 10?”