Grade 2 | MATHEMATICS
WEEK 4 • TEACHER GUIDE AND ANSWER KEY • DAYS 16–20
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 20, read aloud if needed but give no hints.
Week 4 Student Textbook | Week 4 Practice Workbook | Week 4 Teacher Guide | Week 3 Student Textbook | Week 5 Student Textbook | Grade 2 index
Day 16: Add To and Take From
Standard: Grade 2 Math Standard 1, 2.OA.A.1
Worked example: A shelf held 42 jars. Mom added some more jars. Now there are 57 jars. How many jars did Mom add? Worked answer: Mom added 15 jars.
- 59.
- 37.
- 24.
- □ + 16 = 40 (or 40 – 16 = □).
- People got off the bus, so the number on the bus became smaller. Taking away means subtract: 60 – 23 = 37. Accept any answer that connects getting off with taking away.
Teaching note: Have the child act out or draw each story before writing the equation. Start-unknown problems, like Nora’s, are the hardest.
Day 17: Put Together and Take Apart
Standard: Grade 2 Math Standard 1, 2.OA.A.1
Practice record: Fruit stand, printed on the Week 4 Practice Workbook.
Worked example: A garden has 54 flowers. 31 are red and the rest are yellow. How many are yellow? Worked answer: 23 flowers are yellow.
- 63.
- 27 (90 – 63).
- 83.
- 25.
- The drawing shows the whole, 90, split into the parts. Apples and pears make 63, so the plums are the part left: 90 – 63 = 27. Accept any answer that uses the whole and the known parts.
Teaching note: Finding the plums is a two-step problem: first add the known parts, then subtract from the whole.
Day 18: Compare: How Many More or Fewer?
Standard: Grade 2 Math Standard 1, 2.OA.A.1
Practice record: Cans collected, printed on the Week 4 Practice Workbook.
Worked example: A red tower has 46 blocks. A blue tower has 29 blocks. How many more blocks does the red tower have? Worked answer: The red tower has 17 more blocks.
- 16.
- 23.
- Room C.
- 16.
- Both questions ask for the difference between two numbers. The difference is the same whichever way you say it, and subtracting the smaller number from the larger one finds it. Accept any answer about finding the difference.
Teaching note: Children often add in compare problems because they hear the word more. Ask: are we putting groups together, or finding the difference?
Day 19: Two-Step Word Problems
Standard: Grade 2 Math Standard 1, 2.OA.A.1
Worked example: A baker made 40 rolls. She sold 22 in the morning and 9 in the afternoon. How many rolls are left? Worked answer: 9 rolls are left.
- 43 (25 + 30 = 55, then 55 – 12 = 43).
- 17 (35 + 28 = 63, then 80 – 63 = 17).
- 57 (18 + 24 = 42, then 42 + 15 = 57).
- 35 + 28 = 63 and 80 – 63 = 17 (or 80 – 35 = 45 and 45 – 28 = 17).
- Eggs were sold on two different days, so both sales must be taken away from 80. That takes two calculations, even if they are written together as 80 – 35 – 28 = 17. Accept any answer that names the two sales or two calculations.
Teaching note: Accept either order of steps when it is correct. Ask the child to say what each answer means in the story.
Day 20: Independent Check: Word Problems
Standard: Grade 2 Math Standard 1, 2.OA.A.1
Practice record: Library books, printed on the Week 4 Practice Workbook.
Worked example: There are 63 seats. 48 are filled. How many seats are empty? Worked answer: 15 seats are empty.
- 49.
- 63.
- 18.
- □ + 12 = 50 (the answer is 38).
- Returned books come back to the shelf, so the number gets bigger. That means add: 49 + 14 = 63. Accept any answer that connects returning with adding.
Teaching note: Independent check: read aloud if needed, but do not help choose the operation.
Week 4 Student Textbook | Week 4 Practice Workbook | Week 4 Teacher Guide | Week 3 Student Textbook | Week 5 Student Textbook | Grade 2 index