Intro to Rounding for 5th Grade Math

NGSS Science Videos

This video helps children prepare for state math exams by explaining how to solve a retired (released) question from an actual state exam.  - If you want to copy any of our more than 100 free Google Forms (all with questions and links to free-access educational videos we've made), then please download this free file from TPT and it will give you directions for how to access them: https://www.teacherspayteachers.com/Product/State-Math-Test-questions-and-answers-as-a-Google-Form-2022-Q6-10-V2-11530867  Other free resources we've made: - For links to many free educational resources, please visit our website (no 3rd party advertising, no subscriptions, no paywalls): https://TestPrepLLC.org/  - For our free apps for Apple's Mac and iPad (collects no data, no advertising, no subscriptions, no paywalls, no in-app purchases), please visit our page on the Apple App Store. These apps include Common Core and State based practice tests in math, and State science exams based on NGSS and State curriculums (all with detailed, colorful explanations): https://apps.apple.com/us/developer/test-prep-llc/id1727786893  Best wishes, The staff at Test Prep LLC https://TestPrepLLC.org

Transcript

00:00Please see the link in the description to download a worksheet for this video.

00:05If you've not already watched the video on the rounding rainbow,

00:08then we suggest that you watch that before viewing this video.

00:12When ranking something, we want everything to fit perfectly, so we measure distances

00:16very accurately. That applies to small wooden projects. And it applies to big projects,

00:22like planning where a new building will go. In both of these cases, we pay attention to

00:27each decimal in each place value. But there are other times when we don't need to know an exact

00:31number. We just want a rough idea of how big a number is. For example, the distance between New

00:36York and Los Angeles is 2,361 miles, but we often say it's about 2,000 miles. 2,000 miles is a much

00:45simpler number to say because many of the place values are zeros. When we simplify a number by

00:50turning some of its digits to zero, we call this rounding. We use rounding when we just want a

00:56rough idea of a number. For example, these signs show how many people live in three Minnesota towns.

01:03We can simplify these numbers by rounding them. We would say there are about 7,000 people who live

01:08in Belle Plaine, about 7,000 people who live in Jordan, and about 46,000 people who live in Shakopee.

01:16In this video, we'll learn how to round numbers that do not have a decimal point,

01:21what trailing zeros are, and how to round numbers that have a decimal point.

01:27We'll start by learning how to round numbers that do not have a decimal point.

01:31The water is deep in this area of the sea. The passengers ask the captain about how deep it is.

01:37Her depth finder tells her it's 698 feet deep in this area. That's too much detail for the passengers,

01:43so she wants to round it to the nearest hundreds place. What is 698 rounded to the nearest hundreds?

01:51For problems about place values, we recommend that you first draw the rounding rainbow.

01:58Let's start by writing the decimal point and drawing a dashed line. We'll write in the ones

02:02place above the dashed line. Then, we'll draw 5 dashed lines on the left, and 5 on the right.

02:09Each dashed line will be a place value. Then, we draw in the arches that connect the matching

02:14place values on each side. Now, we write the name of the place values for each arch. And finally,

02:20we write a reminder that those on the right side of the decimal have a suffix that says THS. We call

02:26this the rounding rainbow. Here's the original number we want to round. First, we circle the

02:32place value we want to round. In this case, we're going to round the hundreds place value. It's important

02:38to use a circle, as we'll explain shortly. One way to remember to use a circle is because a circle is

02:43round, and we're rounding a place's value. Then, we write the rhyme that tells us how to round. It says,

02:50look next door, if it's more than 4, then add one more. We'll draw a rectangle, which it is the shape

02:57of a door. This is next to the digit we want to round. In this case, the next door digit is a 9.

03:039 is greater than 4, so we'll add 1 to the digit we're rounding. That means the hundreds digit

03:09changes from a 6 to a 7. Here's what the rounded number looks like. Please note that all the digits

03:14to the right of the rounded digit become 0. So, the rounded number is 700 feet. When there are

03:21no digits to the right of the decimal point, we usually simplify the number further by writing it

03:26without a decimal point. The C is about 700 feet deep at this location. Next, we'll talk about

03:33what trailing zeros are. Here are two teddy bears. The price for the one on the right is $12.50.

03:41The one on the left has a price tag that says 12.00. What price is this?

03:46We do not say $12.00. Instead, we say $12.00. With a sensor zero, we only can say the amount.

03:58If we want, we can even leave off the decimal point and the zeros. That's because $12.00.

04:02$12.00 is equal to $12.00. We call these zeros trailing zeros. They're zeros that are on the far

04:11right side of the decimal point and with no other non-zero digits to the right. We can write these

04:17zeros if we want, but most of the time we choose not to write them or to say them. Next, we'll talk

04:22about how to round numbers that have a decimal point. This lady wants to know how far it is from

04:27the shore. Her husband just looked at his GPS and it says they are 4 and 8,375 10,000 miles from shore.

04:38That's too much detail for a casual conversation, so he wants to round it to the nearest tenth of a mile.

04:44What is this rounded to the nearest tenth of a mile?

04:50Here's the original number we want to round. First, we circle the place value we want to round.

04:56In this case, we're going to round the tenths place value. It's important to use a circle.

05:01Then, we write the round that tells us how to round. It says, look next door, if it's more than 4,

05:07then add one more. We'll draw a rectangle which is the shape of a door. This is next to the digit

05:13we want to round. In this case, the next door digit is a 3. 3 is less than 4, so we'll leave the 8 alone.

05:21That means the tenths digit stays as an 8. Here's what the rounded number looks like.

05:26Please note that all the digits to the right of the rounded digit become zero. These are trailing

05:31zeros. They're on the far right of the decimal point, and there are no non-zero digits to their

05:36right. We don't have to write trailing zeros, and it's simpler if we do not write them.

05:41Here's a simpler way to write the final answer. We pronounce this as 4 and 8 tenths. The boat is

05:48about 4 and 8 tenths of a mile from the shore. Thanks for your attention.

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