Rounding Decimals

SYLLABUS DOT POINTS

• Round decimals to a given number of decimal places
• Use symbols for approximation

WORKING MATHEMATICALLY INDICATORS

Students will:

• Explore the process of rounding off decimals to a certain number of decimal places. (Understanding)
• Identify that there are different symbols for approximation. (Understanding)
• Explain the meaning behind different symbols of approximations. (Communicating, Reasoning)

LEARNING GOALS

By the end of this lesson students will be able to:

• Demonstrate how to round off decimals to a certain number of places.
• Explain how to implement the use of various symbols for approximation.

MATERIALS REQUIRED

• Rounding Decimals activity cards
• Laptops
• Whiteboard markers and rubber
• Rounding off decimals worksheet

The main focus of this lesson is to introduce to students the idea of rounding off decimals to a certain number of decimal places. The relevance of doing so would be stressed and real life examples would be referred to in the process. For example track events at the Olympic games could be brought up and how when they record times for runners the event organisers round off an athlete's time. Students would also be made aware of how rounding is a form of approximation. Following on from this, students would then be informed of the symbols for approximation and what they are used for.

INTRODUCTION (15 MINUTES)

Firstly, at the start of the lesson, the teacher would ask students about their homework questions from last class to see if there were any issues. If there was a question multiple students had trouble with the solution would be written on the board and the teacher would go through it step by step.

Following on from this the teacher would then inform the class on what they will be looking at today: Rounding Decimals. An introductory explanation would now occur. It would be initially stressed that rounding off is a way of approximating. A teacher would state that 'rounding off decimals is a procedure whereby we write a decimal with less decimal places in it than we started with by approximating.'

A real life example where the rounding off of decimals occurs would now be explained to the class. The rounding off of the quantity of time would be explored here. For example the teacher could ask students about the Olympics. 'Do you know what the world record is for the 100m sprint?' Here the teacher could inform students that when Usain Bolt's time was recorded they rounded it off to two decimal places.

Continuing on the teacher would then carry out some examples on the board which show students how to round off decimals. The teacher would carefully select the decimals which will be used to avoid confusion. For example they would show students how to round off the numbers 2.357, 0.072, 0.075 and 0.997 to two decimal places. Throughout the explanation questions would be asked to students. For example, 'what do you think we do when we have a five?' and when rounding off 0.997, 'should we leave the .00 in our answer?'

Furthermore it would also be explained to students how there are different symbols for approximation.

BODY (40 MINUTES)

(20 MINUTES)

The body of this lesson will comprise of students completing activities in regards to rounding off decimals. Firstly, students would be instructed to undertake an activity involving decimal cards. (4th Resource Down). For this game students would be allocated into groups. Each group would then get a pool of cards with different decimal numbers on them. They would then be tasked with working together to match up cards (Communicating). Cards are matched up when they have the same place value number. For example 0.2 and 0.25 would match because they both have the number 2 in the tenths column.

Whilst students are playing the game the teacher should move around the room and provide help where it is needed. Once students have played the game twice, solutions would then be written up on the board with the teacher calling for volunteers to come forward and write down their matches and explain why (Reasoning).

(10 MINUTES)

Next students would then be instructed to split into pairs and play an online game which looks at rounding off. Once again the teacher should circulate the room and ensure that students are on task. Once pairs have maybe completed two games each the teacher would then go through a few questions which appeared throughout the game on the board to ensure that students are getting a grasp of the content. (Maybe the hardest questions that appeared could be explained).

(10 MINUTES)

Following on from this the teacher would then encourage students to complete another worksheet that looks at rounding off money (Fluency). Additionally if the worksheet proves to be too easy and repetitive it could be extended by the teacher with a few more questions written on the board that requires students to round off to further decimal places. Upon completion the teacher would then go through the questions and ask students if there was anything that they did not understand.

ASSESSMENT FOR LEARNING AND CONCLUSION (5 MINUTES)

The teacher would then conclude the lesson. The key ideas from the lesson would be reinforced. For example the teacher could stress the convenience of rounding off. 'When we buy items at the shops how many decimal places are the amounts rounded off to?' The teacher would then write up a few quick questions on the board to do with what was learnt today. Students would then be required to answer these and the teacher would then check their answers (AFL).

Homework would also be allocated. For example the teacher could instruct students who did not complete the worksheet to finish it off at home. Alternatively if students have a textbook the teacher could ask students to complete a few carefully selected questions.

LESSON EVALUATION QUESTIONS

Was the card game effective for learning with the students?

Did students enjoy the online game?

Was the worksheet too easy?

Was the introduction too long?