Measuring Small Masses

Grade Level

3rd Grade

Duration

45 minutes

Learning Objectives (Aligned with Common Core Standards)

• I can estimate and measure the mass of objects using grams.
• I can compare the mass of objects using grams.
• I can solve word problems involving mass in grams.

Common Core State Standards (CCSS) Alignment:

• 3.MD.A.1: Solve problems involving measurement and estimation of intervals of time, liquid volumes, and masses of objects.
• 3.MD.A.2: Measure and estimate masses of objects using grams and kilograms and solve related word problems.

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Success Criteria

• Students will accurately measure small objects to the nearest gram on a scale.
• Students will correctly order objects by their mass from lightest to heaviest.
• Students will solve at least two word problems involving addition or subtraction of masses in grams.
• Students will demonstrate understanding by explaining how they measured and compared mass.

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Materials Needed

• Digital or analog kitchen scales capable of measuring grams (preferably 0–200 grams)
• Small common classroom objects (paperclips, erasers, pencils, small toys, etc.)
• Worksheet with word problems and comparison questions
• Whiteboard and markers
• Chart paper or poster with "I can" statements and success criteria
• Timer or clock

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Lesson Breakdown

1. Introduction & "I Can" Statements (5 minutes)

• Write on the board:
  "I can measure things using grams."
  "I can compare masses using grams."
  "I can solve problems with masses."
• Read these statements aloud with the class.
• Explain why measuring mass is important (e.g., knowing how much things weigh helps us buy food, mail packages, and understand the world).

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2. Direct Instruction and Modeling (10 minutes)

• Show a scale and demonstrate how to turn it on and zero it (tare function if available).
• Place a small object (e.g., a paperclip) on the scale.
• Model how to read the number and explain the unit “gram.”
• Show how to compare two items by measuring each and using language like “This pencil weighs more than the paperclip.”
• Discuss estimating mass (e.g., "I think this eraser weighs about 15 grams").
• Write these steps as a simple checklist on chart paper:
  • Turn on and zero the scale
  • Place the object gently
  • Read and record grams
  • Compare masses

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3. Guided Practice (10 minutes)

• Divide students into pairs.
• Give each pair 3 small objects and a scale.
• Students estimate the mass, measure each item in grams, record measurements, and order from lightest to heaviest.
• Circulate to provide support and check accuracy.
• Ask pairs to explain their reasoning about the order to a neighbor or to the teacher.

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4. Application through Word Problems (10 minutes)

• Distribute a worksheet with 3 grade-appropriate word problems that involve:
  • Adding grams (e.g., "If a toy car weighs 45 grams and a ball weighs 30 grams, what's their total mass?")
  • Subtracting grams to find differences
• Model solving the first problem as a class.
• Let students attempt the remaining problems individually or in pairs.
• Discuss the answers together afterward.

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5. Reflection & Sharing (5 minutes)

• Ask several students to share how they figured out which object was heavier.
• Reinforce measurement language and concepts.
• Revisit the “I can” statements; students give a thumbs up if they feel confident.
• Highlight common successes and gently address common misconceptions.

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Differentiation Strategies

Learner Type	Strategy
Struggling learners	Provide objects with clearly different masses to simplify comparison. Use more tactile sensing (hold and feel weight differences). Provide one-on-one support during measurement.
Advanced learners	Challenge to measure items and convert grams to kilograms or estimate combined masses. Introduce estimation challenges — “Which item do you think weighs close to 100 grams?”
English Language Learners	Use visual aids and gestures when introducing the scale and measurement vocabulary. Pair with bilingual partners or use picture dictionaries to define terms like “gram” and “mass.”
Kinesthetic learners	Use hands-on measuring and encourage moving around to gather different objects for mass measurement. Incorporate a “mass hunt” where they find objects around the classroom within 1–100 grams.

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Assessment

• Informal observation during guided practice: Accuracy of measurements and procedures.
• Worksheet word problems assessed for correct calculations and comprehension.
• End-of-lesson exit ticket: Write or say one thing they learned about grams or measuring mass.

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Extensions / Homework Suggestion

• Ask students to find 3 objects at home weighing between 1 and 100 grams and record their guesses and actual measurements with adult supervision, then report back next class.

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This lesson plan’s hands-on approach combined with language integration, collaborative work, and real-life application ensures students build conceptual understanding as defined by the Common Core standards.