Lesson 1.11.1 Small Group · Group 2
Start hereWords, worked example, and sentence starters
Learning target I can describe the ways we are all doers of math, and compare my math story with a classmate's, explain how I can tell, and judge a case I have not seen before.
Start hereWords for this lesson
Read each word before you begin. Say it out loud.
| Word | What it means | Example |
|---|---|---|
| doer of mathSpanish: persona que hace matemáticas | Anyone who uses mathematical thinking — which is everyone, every day. | Splitting a bill 4 ways at dinner — that is a doer of math. |
| math storySpanish: historia matemática | Your own history with mathematics — what you have done, felt, and learned so far. | “In 3rd grade I hated fractions; this year I can explain them.” |
| strengthSpanish: fortaleza | Something you already do well and can share with others. | “I am good at mental math with money” — a strength you can teach. |
| decomposeSpanish: descomponer | To break a number into parts that add, subtract, multiply, or divide back to it. | 78.5 = 70 + 8.5, and also 157 ÷ 2 — both rebuild the same number. |
| estimateSpanish: estimar | A reasoned answer that is close enough to be useful, without counting every one. | 20 cars × about 4 riders ≈ 80 people on the Ferris wheel. |
How it worksWorked example
These numbers are not on your problems. The steps are. Follow them with your own numbers.
A Ferris wheel has 21 cars. Each car holds 5 people. Sam rounds 21 to 20 to estimate. Can one turn carry a line of 102 people?
- Estimate with the rounded number: 20 × 5 = 100
- Compare the estimate to the line: 100 < 102
- Find the exact number of seats: 21 × 5 = 105
- Compare the exact number to the line: 105 > 102
- Yes. One turn carries 105 people, and 105 > 102. The estimate of 100 was too low because Sam rounded down.
Now you trySame steps, your turn
The steps are the same as the worked example. The numbers are yours. Do the work.
Write 78.5 in different ways. Then explain why a subtraction can name the same number.
Say it and write itSentence starters
Finish each sentence out loud with a partner. Then use them in your writing.
Word bank doer of mathmath storystrengthdecomposeestimate
Watch outA common mistake
Believing that 'doing math' only counts when it happens on paper in a classroom.
Lesson 1.11.1 Small Group · Group 2
Group 2Challenge practice
Learning target I can describe the ways we are all doers of math, and compare my math story with a classmate's, explain how I can tell, and judge a case I have not seen before.
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1Complete each step, then write the final answer.
Mark the estimate and the exact count. Compare each with 122. A bus has 31 rows. Each row seats 4 students. Kai rounds 31 to 30 to estimate. Can the bus carry 122 students?
- 1Estimate with the rounded number: 30 × 4.
- 2Is 120 too high or too low? Why?
- 3Find the exact number of seats: 31 × 4.
Final answer: -
2Complete each step, then write the final answer.
A van carries 9 people on each trip. It makes 29 trips. Mo rounds 29 to 30 and says the van can carry 265 people. Is he right?
- 1Estimate with Mo's number: 30 × 9.
- 2Find the exact number of seats: 29 × 9.
- 3Compare 261 with 265. Is Mo right?
- 4Why did the estimate trick Mo?
Final answer: -
3Complete each step, then write the final answer.
Lia estimates 48 × 3 as 50 × 3 = 150. What is the exact answer?
Show your workFinal answer: -
4Complete each step, then write the final answer.
Write 64.5 as a number times 2. What is the number?
Show your workFinal answer: -
5Complete each step, then write the final answer.
A theater has 41 rows with 8 seats in each row. 330 people buy tickets. Estimate with 40 × 8. Then find the exact number of seats.
Show your workFinal answer: -
6Circle the letter of the best answer. Show how you know.
Ty rounds 52 down to 50 to estimate 52 × 7 as 350. Which is true about the exact answer?
- AIt is more than 350.
- BIt is less than 350.
- CIt is exactly 350.
Show your work