Rounding Up or Down to the Nearest Ten
Students will be able to determine whether to round down or up to the nearest ten.
Introduction (15 minutes)
- Invite students to bring their math journals and a pencil to the class meeting area.
- Tell them to place their supplies on the floor next to them.
- Tell the students that today they're going to learn how to round a number to the nearest ten. Let them know that rounding is a way of estimating, where one makes a number less precise but easier to work with.
- Before starting do a short review of place value, in particular the “place” of a digit in a number. On the board write the following "Place: The position of a digit in a number"
- Follow that up by writing "10,000s 1,000s 100s 10s 1s" underneath.
- Let the students know that the place of the digits is important in rounding.
- Tell them in the case of rounding to the Nearest Tens, the ones place is of particular importance. Share the following Rules with the students about rounding to the nearest ten: a. If the digit in the “ones” place is between 0 and 4, round down to the nearest ten. b. If the digit in the “ones” place is between 5 and 9, round up to the nearest ten.
- Let the students know that the rules stand regardless of the size of the number involved.
- Next, come up with a few numbers to model rounding to the nearest ten.
Explicit Instruction/Teacher Modeling (15 minutes)
- Direct the students’ attention to the board.
- Write your chosen example numbers on the board.
- Tell students that the first thing we want to do is determine what the nearest ten, going down and up, is.
- Next, tell the students that we want to look at the number being rounded. Particularly the digit in the ones place.
- Round your example numbers.
- Tell students that if the number already ends in zero then it is already rounded to the nearest ten.
Guided Practice/Interactive Modeling (15 minutes)
- Tell the students to pick up their supplies and write down the following numbers: 27, 188, 1,001 and 4,260.
- Ask them to use the strategy used on the board to round the number 27 to the nearest ten then to round the rest of the given numbers.
- After a few minutes, ask for volunteers to raise their hands and share with the class the steps involved to round the number to the nearest ten.
- As each number is rounded aloud by the class, write down the steps volunteered by the students on the whiteboard.
- Give the students time to finish rounding the numbers given.
- After each of the given numbers are rounded, review them with the class for accuracy. Make sure everyone has the solution after rounding each number given as a reference for completing their assignment during independent work time.
Independent Working Time (30 minutes)
- Send the students back to their seats.
- Pass out the Rounding to the Nearest Ten worksheet.
- Walk around and observe the students as they work on completing the assignment.
- Monitor the students as they work, making sure the problems are done correctly in that they are justifying their answers by showing their work in coming up with the rounded value of each number assigned.
- During this time, ask questions of the students to make sure they understand the concept of rounding a number to the nearest ten.
- Answer questions given by the students, to help them clarify any misconceptions they may have.
- Enrichment: Give your students more challenging numbers to round.
- Support: Observe and monitor these students more closely. Perhaps get involved in helping the students round a number to the nearest ten. You may want to fall back on easier numbers, say just two digit numbers, to begin with, to get them started. They can use manipulatives, such as ten blocks, to visually see how to determine the nearest ten.
Assessment (10 minutes)
- The students will be assessed based on the comments and feedback from them during the lesson about the assignment and at the conclusion of the lesson.
- Check the worksheet for correctness.
Review and Closing (15 minutes)
- Bring the students back to the class meeting area.
- Ask for volunteers to share their answers and work done to complete the problems assigned.
- As the problems are reviewed in front of the class, the students will check their answers for accuracy.
- After each problem has been checked for accuracy, ask the class if there are any questions or comments on rounding a number to the nearest ten.