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# Talk About Rounding Decimals

Boost your students' confidence in verbally sharing their maths processes using grade-level vocabulary! This lesson on rounding decimals can be taught on its own or as support for the lesson Menu maths: Rounding Decimals.
This lesson can be used as a pre-lesson for theMenu maths: Rounding DecimalsLesson plan.
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This lesson can be used as a pre-lesson for theMenu maths: Rounding DecimalsLesson plan.
##### Academic

Students will be able to round decimals to the tenths and ones places.

##### Language

Students will be able to discuss the process of rounding decimals with grade level vocabulary using sentence stems/frames.

(3 minutes)
• Write 2.58 in the middle of a piece of chart paper and engage students in a brain dump session as a whole class in which they say everything they can about this number (some ideas students could give include two point five eight, two point fifty-eight, a decimal, between the whole numbers 2 and 3, etc.).
• Correct or confirm students ideas and record them on the chart in the space surrounding the number.
• Tell students that in the day's lesson they will focus on using year five maths vocabulary to discuss the process of rounding decimals. Have students choral read the student-facing content and lesson objectives.
(8 minutes)
• Show the Vocabulary Cards one at a time on the document camera. Have student volunteers read aloud the definition and describe the image.
• Model using the word AccurateIn a sentence (e.g., "I want to get an accurate solution for this problem."). Place students in partnerships and have them take turns working together to use the tiered words in complete sentences. Invite a few students to share their sentences with the whole group.
• Tell students that knowing the meaning of these key vocabulary words and how to use them properly will help them talk about the decimal rounding they will do in this lesson.
• Inform students that they will practise rounding decimals using a number line and discuss the steps used to do this.
• Remind students what a number line is and show them a variety of examples of number lines with different start and end points. Emphasize the importance of having arrows on both ends of the number line to show that it continues in both directions.
• Tell students that the reason we learn how to round decimals is so that we can perform maths operations with simpler or easier numbers. Tell them that we can round to any place value, such as to the nearest ones, tenths, hundredths.
• Show students a decimal such as 9.45 and label the three place values represented. Have students repeat the names of the place values. Draw a number line between 9 and 10 with 10 equal marks between the two whole numbers. Label each mark as 9.1, 9.2, 9.3, and so on. Circle where 9.45 would be and model your thinking aloud, "I ask myself is 9.45 closer to 9 or closer to 10? I notice that it's closer to 9, therefore I will round down to 9."
• Model your thinking out loud as you round to the nearest tenths using the standard strategy, and compare the rounded numbers. For example, "When I round to the nearest tenths, I underline the digit in the tenths place (4) and I look to the right of this digit. If the number there is 5 or greater, then I round up to 5. If the number is less than 5, then I leave the 4 as is. In this case, the number to the right is 5, so I will round up the 4 to 5. Therefore, 9.45 rounded to the nearest tenth is 9.5."
• Have students contribute their observations about which rounded number is the most accurate. Provide sentence frames to support students as they observe and analyze:
• "I noticed that when I round to the nearest ____, the rounded number is more accurate because ____."
• "I observed that rounding to the nearest tenth place ____, while rounding to the nearest ones place ____."
• Invite students to share their observations with the whole class.
(12 minutes)
• Place students into effective partnerships and make sure they have their maths journals (or lined paper) with them. Tell students that they will round a decimal to the nearest ones and tenths place using a number line or the standard strategy. Encourage students to use the displayed vocabulary cards as a reminder to use the keywords as they work together with their partner and talk about their maths process. Assign them the decimal point 6.83.
• Display the following paragraph frame for students to use in their discussion with their partner:
• "To round the decimal ____(6.83) to the nearest ____(Place value), I first ____. Then, I ____. I noticed that ____. Finally, I rounded it and got ____."
• Have a few students share their discussion with the whole group.
• Invite students to help you create a list of good questions to ask to stimulate more maths conversation. Ideas include:
• How did you know to round up or down? ("I knew I needed to round up/down because...")
• Which process do you find easier to round decimals and why? ("I find it easier to use the____Strategy because...")
• How do you know that your answer is correct? ("I knew the answer is correct because...")
• Which part of the process was hard for you? ("The part when I had to ____Was hard because...")
• Provide a sentence stem/frame for each sample question to help students answer them. Explain that it is important to ask these questions to their partners because we want to make sure we can discuss our maths thinking on a deep level and be able to explain each part of the process.
• Model how you ask these questions to a few students and record their responses.
• Scramble the partnerships so students are working with someone new.
• Repeat the process with two other decimals (14.72 and 9.58) in the new partnerships. One partner gets the first decimal number and the other gets the second one. Tell students to follow these steps:
1. Round to the nearest ones place using a number line or the standard strategy.
2. Share your maths process with your partner using the paragraph frame displayed earlier.
3. Listen as your partner asks you some clarifying questions or questions to deepen your explanation. Respond to the questions.
4. Revise your explanation and retell it to your partner.
• Make sure both partners have a chance to go through the four steps with their partner.
(10 minutes)
• Display a teacher copy of the Rounding Decimals with Number Lines worksheet and hand out a copy to each student.
• Read aloud the directions and review the sample problem.
• Instruct students to complete the worksheet independently. Assist struggling students.
• Have students choose a solution to one of the problems to share with the whole group. Invite students to take turns on each problem to share their maths process in front of the class using the document camera. Encourage students to continue using the sentence stems/frames as an aid to talk about their maths work.
• Correct or confirm students' discussion.

Beginning

• Provide bilingual resources such as online dictionaries or glossaries to help students look up unknown vocabulary words in their home language (L1) or in English (L2).
• Pair students with advanced ELs who are able to assist them in the partner activity.
• Pull aside a small group of struggling students and have them do the guided work with you.
• Have students repeat and rephrase the directions in the lesson.

Advanced

• Ask students to rephrase instructions and important learning points throughout the lesson.
• Encourage students to converse with their partners without using the sentence stems/frames for support.
• Have them be first to share their maths processes during group sharing time.
(4 minutes)
• Distribute a sticky note to each student. Have them write a decimal number on the sticky note and choose the place value to round up to (ones or tenths).
• Collect the sticky notes and redistribute them to students, making sure that no one got their own decimal.
• Tell students to round the decimal to the nearest place value written on the sticky note. Have students submit their sticky note to you as an exit ticket.
(3 minutes)
• Invite students to reflect on the experience of discussing their maths thinking with a partner, using the following questions as a guide:
• What was it like to have to answer questions about your maths thinking? ("I thought it was ____When I had to answer questions about my maths thinking.")
• Do you feel that you are more confident in talking about maths when you get the chance to discuss with a partner and why? ("I feel that I am/am not more confident in talking about maths when I get to talk with my partner because...")
• Have students go around and reflect on the lesson orally. Then, remind students that it is important to be able to round decimals so that they can add, subtract, or make other maths estimates easily and quickly when they see decimals.

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