The purpose of this activity is for students to revisit numbers that are written in different forms. Students match numbers represented in different forms: base-ten numerals, base-ten diagrams, number names, and expanded form. As they make matches, students use their understanding of base-ten structure represented in different ways (MP7).

• “What does each digit in the number represent?”
• “How could we use what each digit represents to match it to another representation?”

• Invite students to share the groups they made and how they know those cards go together.
• Attend to the language that students use to describe their matches and numbers in different forms, and give students opportunities to describe more precisely the numbers in different forms.
• Highlight the use of terms such as “hundreds,” “tens,” “ones,” “word form,” “expanded form,” “base-ten blocks,” and “base-ten diagrams.”

The purpose of this activity is for students to use place-value understanding from grade 2 to decompose numbers in different ways. In small groups, students start by writing a three-digit number, and then pass their number to the group member at their right. Each time students receive the number, they decompose it in a different way. In the Activity Synthesis, students look for connections in the ways their number was decomposed, and in all the recording sheets in their group. Highlight connections that show that place value can be used to represent a number as different combinations of hundreds, tens, and ones. This will be helpful later in the unit when students add and subtract, using strategies and algorithms based on place value.

• “How did you decompose the number?”
• “How could you use base-ten blocks to come up with other ways to decompose the number?”

• Have groups share the connections they saw across the sheets.