2nd Grade Everyday Math Lesson 10.8

Summary

The lesson introduces place value and base-ten representations through a money scenario, student demonstrations, and a read-aloud story about zero.

Main Ideas and Activities

Learning goals: Students practice counting by ones, tens, and hundreds, and modeling and writing three- and four-digit numbers with base-ten blocks.

Making the largest number: Students use the digits 1, 5, and 9 exactly once to create an amount of money. The class determines that 951 is the greatest possible number because the largest digit belongs in the greatest place-value position: 9 in the hundreds place is worth 900, while 9 in the ones place is worth only 9.

Representing place value: Students take the roles of hundreds, tens, and ones, then use base-ten blocks to show a number. For example, 2 hundreds, 4 tens, and 2 ones form 242.

The teacher adds a thousands block to 242 to make 1,242. The hundreds, tens, and ones retain their values, while the new block represents one thousand.

Students also build 1,362 with base-ten blocks:

• 1 thousand block
• 3 hundred-flats
• 6 ten-rods, called “longs” in the lesson
• 2 unit cubes

What zero does: Students discuss whether adding a zero changes a number. Adding zero to a number does not change its value, but placing a zero at the end of a number can create a larger number by shifting the other digits into higher place-value positions. For example, appending a zero to 1,362 makes 13,620.

Read-Aloud: A Place for Zero

The teacher reads a story in which Zero initially feels useless because adding zero leaves a number unchanged. Zero discovers several mathematical roles:

• Additive identity: Adding zero to a number leaves it unchanged.
• Multiplicative zero property: Multiplying a number by zero gives zero.
• Placeholder: Zero helps create and write numbers such as 10, 30, and 100.

The story connects zero’s role as a placeholder to the lesson’s broader idea that a digit’s position determines its value. The class prepares to move on to the math journals, but the subtitles end before that work begins.

Speakers and Sources

• Classroom teacher/instructor: Leads the lesson, asks questions, demonstrates with base-ten blocks, and reads the story.
• Students: Answer questions, discuss ideas with partners, and demonstrate place-value roles. Some names in the subtitles may be inaccurate because of automatic transcription.
• Read-aloud source: A Place for Zero. The teacher identifies Angelina Sparagna as the author and Phyllis Hornung as the illustrator, though the subtitles around the credits are garbled. The story features fictional number characters, including Zero, Count Infinity, King Multiplus, and Queen Addaline.