The purpose of this activity is for students to represent a two-digit number in as many ways as they can. Students are given two number cards and use them to make a two-digit number. Students create a collection with connecting cubes in towers of 10 and singles to represent their number. Then students represent their number in as many different ways as they can on paper. Representations may include base-ten diagrams, _____ tens _____ones, and expressions that show the tens and ones.

The collections students make are used in the next activity.

• “Para descifrar cómo formar la colección de cubos encajables, ¿cómo usaron los dígitos del número de 2 dígitos que crearon?” // “How did you use the digits in the 2-digit number you created to figure out how to make the collection of connecting cubes?” (I know the digit on the left shows how many tens, so we chose that many towers of ten. The digit on the right shows how many ones, so we chose that many single cubes.)
• “¿Como usaron los dígitos para crear otras representaciones?” // “How did you use the digits to create other representations?” (I used the digits to see how many tens and ones to draw. I know the digit on the left means tens and the other digits are ones, so I wrote __ tens and __ ones.)
• “Ahora van a hacer un recorrido por el salón. Observen otras colecciones y muéstrenlas de todas las formas que puedan” // “Now you will do a Gallery Walk, observe other collections, and show them in as many ways as you can.”

The purpose of this activity is for students to represent a collection of tens and ones in as many ways as they can. Students participate in a Gallery Walk. Students visit at least four collections, represent them in different ways, and then compare their representations with their partner. Students may represent the collections in any ways they choose, such as base-ten drawings with and without showing all the ones within each ten, _____ tens _____ ones, expressions that show the tens and ones, or another way that makes sense to them, including writing the 2-digit numbers.

Students can choose which collections they would like to visit or the teacher can assign the collections. During the activity synthesis, students make connections between representations.

This activity uses MLR7 Compare and Connect. Advances: Representing, Conversing.

If students only use one type of representation, consider asking:

• “¿De qué otra forma puedes mostrar esta colección?” // “What’s another way you can show this collection?”
• “¿Cómo puedes usar palabras para describir esta colección? ¿Cómo puedes usar números y símbolos?” // “How can you use words to describe this collection? How can you use numbers and symbols?”

MLR7 Compare and Connect

• Find a new partner and share the representations you made.
• Discuss how your representations are alike and how they are different.
• Invite 2–3 groups to share what they discussed.

The purpose of this activity is for students to choose from activities that offer practice adding and subtracting within 20, or estimating, counting and representing quantities. Students choose from any of the previously introduced stages of the listed centers. They are encouraged to choose the center that will be most helpful for them at this time.

• Grab and Count
• Counting Collections
• Shake and Spill
• Check It Off

• “Kiran está jugando ‘Agarra y cuenta‘. Organizó sus cubos en 3 grupos de 10 y 1 unidad. ¿Cuántos cubos tiene?” // “Kiran is playing Grab and Count. He organized his cubes into 3 groups of ten and 1 one. How many cubes does he have?”