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Reteach Unit 3, Lessons 4-6

Grade 2 | 90-minute Lesson | 14 Students

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Learning Objective

• Students will reinforce understanding of measuring lengths using appropriate tools and units (inches, centimeters).
• Students will practice reading, writing, and comparing three-digit numbers to understand place value within 1000.

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Common Core Standards

• 2.MD.B.6: Measure the length of an object twice, using length units of different lengths for the two measurements; describe how the two measurements relate to the size of the unit chosen.
• 2.NBT.A.2: Count within 1000; skip-count by 5s, 10s, and 100s. Read and write numbers to 1000 using base-ten numerals, number names, and expanded form.

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Key Vocabulary

• Length
• Inches
• Centimeters
• Unit
• Measure
• Place value
• Hundreds
• Tens
• Ones
• Expanded form
• Skip counting

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Materials Needed

• Rulers (inches and centimeters) – 1 per student
• Measuring tapes or yardsticks
• Number cards (hundreds, tens, ones)
• Whiteboards and markers
• Place value charts
• Counting objects (blocks, dots, stickers)
• Worksheet: Measurement table + place value problems

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Lesson Sequence

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Hook (Launch/Warm-Up) – 10 minutes

Activity: “How long is your desk?”

• Begin by asking students to look around the classroom and guess the length of their desk or an object nearby in inches or centimeters.
• Write their guesses on the board.
• Show both an inch ruler and a cm ruler, briefly comparing sizes.
• Connect to everyday experiences: “We use different units to measure things all the time!”

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Learn (Explore)

Mini-lesson (I Do) – 15 minutes

Focus: Measuring lengths with different units and understanding place value.

• Model measuring a pencil first with an inch ruler, then with a cm ruler. Write down the measurements.
• Ask students: “Which measurement is bigger? Why?” Highlight the difference in unit size.
• Introduce place value charts and demonstrate reading and writing a three-digit number (e.g., 374).
• Show how to break numbers into hundreds, tens, and ones using expanded form.
• Use skip counting by 5s, 10s, and 100s on a number line to reach numbers near 1000.

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Guided Practice (We Do) – 25 minutes

Activity 1: Measuring Objects

• Split class into pairs, each with rulers.
• Give 3 classroom objects to measure using both inches and centimeters.
• Students record measurements on mini-whiteboards.
• Discuss differences and encourage students to use vocabulary: “Inches are longer units than centimeters...”

Activity 2: Place Value Game

• Use number cards – students build three-digit numbers.
• On whiteboards, write the number, then write it in expanded form.
• Practice skip counting sequences together on chart paper.

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Independent Practice (You Do) – 20 minutes

Worksheet:

• Part A: List 5 objects in the classroom and measure them with both rulers. Write two measurements for each.
• Part B: Given three numbers, write them in expanded form and compare which is greater/lesser.
• Part C: Using skip counting, fill in missing numbers in sequences (by 5s, 10s, 100s).

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Closing (Synthesis/Discuss) – 10 minutes

• Regroup and ask volunteers to share one measurement they took and explain why measurements differ with inches vs. cm.
• Ask for volunteers to share a number they expanded and explain place values.
• Review the importance of measuring with different units and understanding place value for math fluency and real life.

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Fluency Focus

• Skip counting by 5s, 10s, and 100s through chants and claps.
• Quick place value flashcards: Teacher shows a number, students write expanded form quickly on mini-whiteboards.

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Differentiation

• For Struggling Learners:

  • Use number lines and physical blocks to build numbers for place value.
  • Provide rulers with larger, clearer markings.
  • Partner with a peer or adult for guided measurement.

• For Advanced Learners:

  • Challenge with mixed unit conversion questions (e.g., “How many centimeters in 2 inches?” – simplified).
  • Introduce comparing numbers using >, <, = symbols.

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Assessment

• Formative: Observe and take notes during guided and independent practice—check for correct measuring techniques and place value understanding.
• Cool Down: Exit ticket – each student writes one measurement and one three-digit number in expanded form with a quick explanation.
• Optional End of Unit Checkpoint: Mini quiz on measurements and place value concepts covered.

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Teacher Notes

• Ensure rulers are accessible and usable for all students before the lesson.
• Reinforce vocabulary visually and verbally throughout.
• Use praise to motivate participation, especially when students use correct mathematical vocabulary.
• Use this lesson as a reteach opportunity to solidify concepts in an engaging, hands-on way.

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This lesson blends measurement and place value to deepen conceptual understanding while supporting foundational fluency for 2nd graders aligned with Common Core standards 2.MD.B.6 and 2.NBT.A.2. The mix of visual, tactile, and verbal strategies ensures accessibility and engagement for every student.