Rounding Whole Numbers
Students will be able to round whole numbers to the nearest ten or hundred using a number line as a tool.
- Explain that today, the class is going to be talking about rounding numbers.
- Tell students, "We round numbers all the time. For example, your family might ask you how many students are in your class. You might respond by saying there are about 20 students in your classroom. There may be 19 or 21, but you know there are about 20 students in your classroom, so you round to the nearest ten.
- Explain that rounding just means figuring out which 10 or 100 is closer to a number.
- Ask your students to share other examples of rounding.
Explicit Instruction/Teacher Modeling(10 minutes)
- Draw a simple number line on the board with intervals of 10 from 0 to 50.
- Place a dot on 43 and write 43 above the dot.
- Explain that you can use a number line to help you figure out which ten the number you're trying to round is closer to.
- Ask, "Which ten is 43 closer to, 40 or 50? How do you know?"
- Draw another simple number line on the board with intervals of 100 from 100 to 500.
- Explain that a number line doesn’t always have to start at 0. It can start at any number, but the jumps have to be the same.
- Place a star on 189 and write 189 above the star.
- Ask, "What 100 is closer to 189? How do you know?"
Guided Practice/Interactive Modeling(15 minutes)
- Distribute the Rounding to the Nearest 10 or 100 worksheet.
- Go over the worksheet's instructions.
- Work through questions 1-4 as a class.
Independent Working Time(20 minutes)
- Have students complete the rest of their worksheets independently.
- Enrichment: Students who finish early or need an extra challenge can draw their own number line on the back of the worksheet. Challenge them to draw their own intervals, place a dot on the number line, and round it to the nearest ten or hundred.
- Support: Some students may find it difficult to place a dot in the correct place on the number line during Independent Working Time. It may be helpful to have the dots already placed for them so they can focus more on rounding.
- Give each student a sticky note.
- Give students the following problems to solve: 1. Round the number 157 to the nearest ten. 2. Round the number 84 to the nearest hundred.
- Have students write down their answers on their sticky notes.
- Collect the notes and review them later to assess students' understand of the lesson content.
Review and Closing(5 minutes)
- Ask students some closing questions: Why is it helpful to know how to round numbers? How can we use a number line to help us round to the nearest ten or hundred?