Operations: Dividing Decimals

SYLLABUS DOT POINTS

• Determine the effect of multiplying or dividing by a number with magnitude less than one
• Multiply and divide decimals by powers of 10
• Multiply and divide decimals using written methods, limiting operators to two digits
• Multiply and divide decimals using a calculator

WORKING MATHEMATICALLY INDICATORS

Students will:

• Use appropriate methods to divide decimals by numbers with magnitudes less than one. (Problem Solving, Understanding)
• Identify the process for multiplying decimals by powers of 10. (Understanding)

LEARNING GOALS

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

• Demonstrate how to divide a number that is of a magnitude less than one.
• Identify how to divide decimals by powers of 10. (With close notice of the positioning of the decimal point itself).
• Be able to divide decimals using both written and calculator methods.

MATERIALS REQUIRED

• Dividing decimals worksheet
• Laptops
• Whiteboard markers and rubber

Following on from last lesson, which looked at multiplication, students would now move onto looking at dividing decimals. The class structure would be similar to the last whereby dividing by powers of 10 would be looked at first. Following this, dividing a decimal by a whole, using short division, where the divisor is a whole number would be explored next. Students would move onto looking at dividing decimals by other decimals. First they would be shown how to do so using written methods and then they would compute some questions using a calculator.

INTRODUCTION (15 MINUTES)

Initially the homework from last lesson would be looked at. If there were any particular questions students had any issues with the teacher would address these on the board. Students would now be informed that this lesson will focus on looking at the idea of dividing decimals. A demonstration would now occur on the board. For this, the teacher could explain how to complete a few examples. For example, they could first go through a questions that looks at dividing a decimal by powers of ten. The teacher could ask, ‘last lesson when we multiplied we moved the decimal point to the right. Which way do you think the decimal point is going to move if we divide instead?’

Next, another example would be looked at which involves a decimal number being divided by a whole number. Finally, the teacher would then demonstrate an example that looks at a decimal being divided by another decimal using the written method. Here the teacher could say 'when you are dividing decimals by decimals the most important thing is to make the second decimal, the divisor, a whole number.'

BODY (25 MINUTES)

Following on from this, students would be instructed to complete the provided worksheet that looks at the division of decimals. For this, they would be instructed to work in pairs. The teacher would encourage students to first complete the questions by hand (Fluency). Once they have finished all of the questions the teacher would then tell students to check their answers using Microsoft Excel. Once all students have had a chance to do this answers would be checked on the board. For this the teacher could get volunteers to come up and write the solutions. Once this is finished the teacher would then instruct students to experiment with Excel and carry out their own questions. Whilst this is occurring the teacher would move throughout the room and make sure students are on task.

ASSESSMENT FOR LEARNING AND CONCLUSION (20 MINUTES)

(15 MINUTES)

Following the end of class the teacher would then make students complete a short quiz which looks at the operations of decimals (AFL). So there would be a few questions on addition, subtraction, multiplication and division. The purpose of this would be to ensure that students are coping okay with completing operations with decimals. Once students have had a few minutes to complete the short quiz the teacher would then go through the solutions.

(5 MINUTES)

The teacher would re-emphasise they key ideas from today. For example the teacher could say, 'Remember there are three types of division. 1. Dividing by 10 or a power of 10. 2. A decimal divided by a whole number. 3. And a decimal divided by a decimal. The first is the easiest and the second and third are a little bit more difficulty.' For homework the teacher could then allocate some carefully selected textbook exercises that look to consolidate what was learnt today.

LESSON EVALUATION QUESTIONS

Was it a good idea getting students to check their answers using Excel?

Did students work well in pairs?