Using place value understanding and properties of operations to perform multi-digit arithmetic

Students' Responses to Task. Good thinking kiddies 👍

Review and extra Practice for Math Test #1

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Rounding Prices

Minds On Question

Modified Minds On Question

Students' Response

Notice the different strategies used by students. 

- Add all the prices, then round off the answer ($12, 479) to the nearest ten thousands ($12,000)

- Round off the total ($12, 479) to the nearest thousands, hundreds and tens
$12, 000  (1000s)                  $12, 500 (100s)                                 $12, 480 (10s)

- Round off each price individually then add to find the answer
$2,473 rounded off to the nearest thousands - $2,000
$6,923 rounded off to the nearest thousands - $7,000
$3,083 rounded off to the nearest thousands - $3,000

                                                              Total: $12,000

Comparing and Ordering Whole Numbers

In these lessons, students focused on comparing whole numbers using two strategies:
1) using a place value chart and observing the number of digits
2) using a number line to locate benchmarks (or friendly numbers)

Comparing numbers led to a discussion on Rounding numbers. Rounding to the nearest tens, hundreds, thousands, ten thousands.

Students were then given a collaborative task to work on in small groups.

Posters of students' work

 We had a Math Congress to discuss students' interpretation of the question. It was a rich, lively debate as to whether Ms Rashid  was indeed right or not. Most students picked up on the significance of "about"when asked which word guided their understanding of the question. They associated it with 'rounding', 'estimate' and 'almost'.

The conclusion at the end was that Ms Rashid was right in saying the two jars had about the same amount of stickers if both numbers were rounded off to the nearest thousands. 3425 rounded down is 3000 and 2768 rounded up is 3000. However, most students were quick to point out that rounding in this case does not present a clear or accurate picture when comparing numbers. Many students thought the 657 difference was too large.

For the students that believed Ms Rashid was wrong, they were able to justify their thinking on the grounds that if both numbers were rounded off to the nearest tens or hundreds then the amount of stickers in both jars would NOT be about the same.

CONCLUSION: She is right and wrong depending on whether the numbers were rounded to the nearest tens, hundreds or thousands.

Excellent job kiddies!!!!