Operations: Moving onto the Multiplication of 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

WORKING MATHEMATICALLY INDICATORS

Students will:

• Use appropriate methods to multiply decimals by numbers with magnitudes less than one. (Problem Solving, Understanding)
• Demonstrate what happens to decimals when they are multiplied by powers of 10. (Understanding)
• Identify the idea of a number growing smaller or larger when multiplied by a decimal. (Understanding)

LEARNING GOALS

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

• Demonstrate how to add and subtract decimals.
• Explain what happens when a number is multiplied by a magnitude less than one.
• Demonstrate how to multiply decimals by powers of 10. (With close notice of the positioning of the decimal point itself).

MATERIALS REQUIRED

• Addition and subtraction of decimals worksheet
• Laptops
• Whiteboard markers and rubber

The initial part of this lesson would be on re-accustoming students with operations and decimals. This would be achieved through firstly revising addition and subtraction of decimals with students first. This would ensure that any discrepancies or holes from their stage 3 learning would be covered. Students' minds would also once again get used to associating decimals with operations. This would therefore put them in the best opportunity to be open to learning new operations with decimals.

Following on from this students would then be introduced to the idea of multiplying decimals. The effects of multiplying a number with a decimal less than one will be demonstrated to the class. Next students will then get the opportunity to multiply decimals by powers of 10. This will then put them on the best platform for the next lesson which looks at decimals multiplying with other decimals.

INTRODUCTION (10 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. Furthermore, the teacher would also write down another question that did not appear in their homework that was related to last lesson. The purpose of this would be to ensure that all students are confident with what was learnt previously.

Following on from this, it would be revealed to students that this lesson would look at operations involving decimals. The teacher would say that, ‘although the purpose of this lesson would be to eventually get to multiplying decimals, I first thought that we should have a look at adding and subtracting them, just to make sure you are all confident with doing this.’ The teacher would then do two examples on the board. One to do with addition and then one to do with subtraction. When explaining, the teacher could ask, ‘do we line up the decimal points?’

BODY (45 MINUTES)

(15 MINUTES)

Once the teacher has gone through the examples, the worksheet on the addition and subtraction of decimals would be handed out (It is the 1st Resource Down). Students would then be instructed to complete this individually. Whilst this is occurring the teacher would circulate the room to ensure all students are on task. If there are any questions from students the teacher would also help. Once students have had about ten minutes the solutions would then be completed on the board.

(15 MINUTES)

The next part of the lesson would involve the teacher introducing to students the idea of multiplying decimals. The teacher would first explain what would happen to a number if it is multiplied by another number that has a magnitude less than one. For example, the teacher could demonstrate 1 multiplied with 0.5. Once the teacher has finished explaining this they would then introduce the idea of multiplying decimals by the powers of 10. Whilst explaining with a few examples the teacher could ask questions like, 'when I multiply this by ten how many times do I move the decimal place?’ and ‘am I moving it to the right or left?’

(10 MINUTES)

Following this the teacher would instruct students to form pairs and play the online game which involves multiplying decimals with cars (It is the 2^nd resource down). Whilst this is occurring the teacher would move throughout the room to ensure that students are actually playing the game and not becoming distracted by anything else.

ASSESSMENT FOR LEARNING AND CONCLUSION (10 MINUTES)

The teacher would re-emphasise they key ideas from today. For example they could ask, ‘when dividing a decimal by 100 which way do I move the decimal point and how far?’ The teacher would then hand out a small quiz for students to complete quickly (AFL). The teacher would then collect these and mark them overnight. This would provide the teacher with valuable insights into how the students are going. For homework the teacher could then allocate some carefully selected textbook exercises that look at consolidating what was learnt today.

LESSON EVALUATION QUESTIONS

Was there too much content in this lesson?

Was it necessary to address prior knowledge and go over the operations of addition and subtraction first?

Was the online game beneficial for students?

Were they engaged whilst playing it?