Ahava~Love Assembly

Grade 2 Mathematics Week 9 | Teacher Guide

Grade 2 | MATHEMATICS

WEEK 9 • TEACHER GUIDE AND ANSWER KEY • DAYS 41–45

Read each lesson aloud with the child and model the worked example before practice. Do not show this key during practice. Accept oral, drawn or written answers where the child cannot yet write the whole answer. On Day 45, read aloud if needed but give no hints.

Week 9 Student Textbook | Week 9 Practice Workbook | Week 9 Teacher Guide | Week 8 Student Textbook | Week 10 Student Textbook | Grade 2 index

Day 41: Estimate Lengths

Standard: Grade 2 Math Standard 19, 2.M.A.19

Practice record: Estimate or measure, printed on the Week 9 Practice Workbook.

Worked example: A stapler is about as long as 6 large paper clips in a row. Estimate its length in inches. Worked answer: About 6 inches.

  1. The doorway height.
  2. 1 inch (9 – 8).
  3. 6 centimeters (15 – 9).
  4. 8 centimeters.
  5. You can picture how many fingertips fit along the object. That number of fingertips is about the number of centimeters. Accept any answer that uses the fingertip as a measuring guide.

Teaching note: Encourage estimates before every measurement this week. A household doorway is about 2 meters tall.

Day 42: How Much Longer?

Standard: Grade 2 Math Standard 20, 2.M.A.20

Practice record: Snake models, printed on the Week 9 Practice Workbook.

Worked example: A blue ribbon is 14 inches long. A red ribbon is 9 inches long. How much longer is the blue ribbon? Worked answer: The blue ribbon is 5 inches longer.

  1. 6 centimeters.
  2. 8 centimeters.
  3. 14 centimeters.
  4. The green and yellow snakes (6 centimeters apart).
  5. Inches and centimeters are different sizes. To compare lengths, both objects must be measured in the same unit. Accept any answer about using the same unit.

Teaching note: Have the child lay real objects side by side to see the extra length before subtracting.

Day 43: Length Word Problems

Standard: Grade 2 Math Standard 21, 2.M.B.21

Worked example: A path is 45 feet long. Workers add 28 more feet. How long is the path now? Worked answer: The path is 73 feet long.

  1. 36 inches.
  2. 57 centimeters.
  3. 62 meters.
  4. 18 centimeters.
  5. 85 – ? = 49, or 49 + ? = 85. The piece was 36 inches. The whole board minus the cut piece leaves 49 inches. Accept either equation with 36 inches.

Teaching note: Ask the child to draw a bar for each length. The picture shows whether the problem joins lengths or finds a difference.

Day 44: Lengths on a Number Line

Standard: Grade 2 Math Standard 22, 2.M.B.22

Worked example: Use a number line to find 36 + 25. Worked answer: 36 + 25 = 61.

  1. 78.
  2. 51.
  3. 73 (jump 10 to 67, then 6 to 73).
  4. 55 (back 30 to 60, then back 5 to 55).
  5. Start at 0 and jump to 23. Then jump forward 18 more: 10 to 33 and 8 to 41. The snail went 41 centimeters in all. Accept 41 with a description of the jumps.

Teaching note: Draw a number line from 0 to 100 marked by tens, and let the child draw the jumps as arcs.

Day 45: Independent Check: Estimate, Compare and Solve

Standard: Grade 2 Math Standard 19, 2.M.A.19; Grade 2 Math Standard 20, 2.M.A.20; Grade 2 Math Standard 21, 2.M.B.21; Grade 2 Math Standard 22, 2.M.B.22

Worked example: A green crayon is 9 centimeters and a red crayon is 7 centimeters. How much longer is the green crayon? Worked answer: 2 centimeters longer.

  1. 2 meters.
  2. 18 feet.
  3. 82 meters.
  4. 34.
  5. She gives some away, so subtract: 72 – 25 = 47. She has 47 centimeters left. Accept 47 with subtraction or counting back on a number line.

Teaching note: Independent check: read aloud if needed, but do not help with the answers.

Week 9 Student Textbook | Week 9 Practice Workbook | Week 9 Teacher Guide | Week 8 Student Textbook | Week 10 Student Textbook | Grade 2 index