Ahava~Love Assembly

Grade 2 Mathematics Week 6 | Teacher Guide

Grade 2 | MATHEMATICS

WEEK 6 • TEACHER GUIDE AND ANSWER KEY • DAYS 26–30

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 30, read aloud if needed but give no hints.

Week 6 Student Textbook | Week 6 Practice Workbook | Week 6 Teacher Guide | Week 5 Student Textbook | Grade 2 index

Day 26: Add or Subtract 10 in Your Head

Standard: Grade 2 Math Standard 13, 2.NBT.B.13

Worked example: What is 472 + 10? Worked answer: 472 + 10 = 482.

  1. 628.
  2. 240.
  3. 713.
  4. 506.
  5. Adding 10 adds one ten. The 1 ten becomes 2 tens, and no hundreds or ones are added. Accept any answer about adding one ten.

Teaching note: Use a hundreds chart or place-value chart. Question 4 crosses a hundred, so the hundreds digit also changes.

Day 27: Add or Subtract 100 in Your Head

Standard: Grade 2 Math Standard 13, 2.NBT.B.13

Worked example: What is 836 – 100? Worked answer: 836 – 100 = 736.

  1. 345.
  2. 807.
  3. 460.
  4. 250, 350, 450.
  5. She changed the tens digit instead of the hundreds digit. Adding 100 adds one hundred, so 412 + 100 = 512. Accept any answer that names the hundreds place.

Teaching note: Contrast Day 26 and Day 27 side by side: plus 10 changes the tens, plus 100 changes the hundreds.

Day 28: Add Three-Digit Numbers with Models

Standard: Grade 2 Math Standard 12, 2.NBT.B.12

Worked example: Add 321 + 245. Worked answer: 321 + 245 = 566.

  1. 547.
  2. 857.
  3. 570.
  4. 598.
  5. Draw 1 square, 3 sticks and 2 dots for 132, and 4 squares, 1 stick and 5 dots for 415. Count 5 squares, 4 sticks and 7 dots, which is 547. Accept any drawing that matches each place.

Teaching note: Today’s problems need no regrouping. Insist on lining up each place.

Day 29: Regroup When Adding Within 1000

Standard: Grade 2 Math Standard 12, 2.NBT.B.12; Grade 2 Math Standard 12, 2.NBT.B.12a

Worked example: Add 247 + 136. Worked answer: 247 + 136 = 383.

  1. 483.
  2. 437.
  3. 635.
  4. The tens: 6 tens + 7 tens = 13 tens, so 10 tens become 1 hundred.
  5. The tens add to 8 + 4 + 1 = 13 tens, which is more than 9. Ten tens equal one hundred, so 10 tens are traded for 1 hundred, leaving 3 tens. Accept any answer that says ten tens make one hundred.

Teaching note: Model each trade with blocks before written work. Children should be able to say what the small 1 means.

Day 30: Independent Check: Mental Math and Adding Within 1000

Standard: Grade 2 Math Standard 13, 2.NBT.B.13; Grade 2 Math Standard 12, 2.NBT.B.12; Grade 2 Math Standard 12, 2.NBT.B.12a

Practice record: Fruit trees, printed on the Week 6 Practice Workbook.

Worked example: What is 530 + 100? Worked answer: 530 + 100 = 630.

  1. 599.
  2. 884.
  3. 563.
  4. 328.
  5. Yes, in the ones place. 5 + 8 = 13 ones, so 10 ones were traded for 1 ten. The tens were 4 + 1 + 1 = 6, so no other trade was needed. Accept any answer that names the ones place.

Teaching note: Independent check: read aloud if needed, but do not help with the answers. Question 1 crosses a hundred going down.

Week 6 Student Textbook | Week 6 Practice Workbook | Week 6 Teacher Guide | Week 5 Student Textbook | Grade 2 index