Calculating Decimals of Quantities

SYLLABUS DOT POINTS

• Multiply and divide decimals using a calculator
• Calculate decimals of quantities using mental, written and calculator methods

WORKING MATHEMATICALLY INDICATORS

Students will:

• Identify the appropriate equivalent form for mental computation. For example 0.25 of $60 is equivalent to $60 divided by 4. (Communicating)

LEARNING GOALS

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

• Demonstrate how to calculate decimals of quantity using written and calculator methods.

MATERIALS REQUIRED

• Small whiteboards
• Different quantities worksheet
• Whiteboard markers and rubber
• Laptops
• Textbooks

The main focus of this lesson would be to build on student's knowledge of operations with decimals so that they may now use decimals to calculate an amount of a quantity. The first part of the lesson would involve describing to students what a quantity is. It would be stressed that a quantity is something which can be measured, for example money, mass, height, length, distance etc.

The idea of calculating decimals of quantities would then be introduced to students. It would be stressed that this is simply just a matter of multiplying a decimal with the particular quantity. It would be emphasised that this in mathematics is known as "of." So for example calculate 0.65 of 1km, which is in turn equivalent to 0.65 multiplied by 1000m. Furthermore it would also be highlighted that decimals need not be less than one. For example you might get a question with a question like 1.25 times 1km. So the decimal is not necessarily going to be less than one.

INTRODUCTION (15 MINUTES)

The idea of quantities would be looked at first. The teacher would reinforce to students what a quantity is. Before explaining the teacher could first ask students, 'can you give me some examples of different quantities?' Following on from this the teacher would then explain that a quantity is something that can be measured. For example length, time, mass, volume, temperature etc.

Once this has been explained the teacher would then inform students that today they will be looking at calculating decimals of quantities. Here the teacher could bring up a real life scenario to explain what this means. For example the teacher could talk about buying fruit from a supermarket. For example the teacher could say something like, 'I want to buy apples from Coles and they are $5/kg. I pick some apples, and their combined weight is 500g. How much do I pay?' The solution would then be completed on the board for students to copy and refer to later on when completing similar questions.

BODY (40 MINUTES)

(15 MINUTES)

Delving into the body of the lesson, students would first complete the activity which looks at ordering different types of quantities. (It is the 1st resource down). For this, students would be instructed to split into small groups and work through the questions together. For this particular exercise, small whiteboards would be provided to each group for working out. Whilst the teacher is walking around the room questions like, 'can you think of another example of the quantity of speed that is faster than the ones here?' or 'can you tell me another quantity that does not appear on this worksheet?' could be asked.

(20 MINUTES)

Once students have had enough time to work through the quantities exercise the teacher would then ask students to complete some exercises on calculating various decimals of quantities from their textbook. Suitable questions would be chosen and the teacher would make sure that the questions students are doing are not repetitive. Students would be instructed to remain in their same groups and complete the questions together. Whilst this is occurring, the teacher would set up a "Web Whiteboard" page that all students can access. (It is the 3rd Resource Down). The teacher would encourage students to then record any questions that they may be having difficulty with on the page. Once students have been given some time the teacher would then call for the class to stop. What would then occur is the teacher would look at the questions posted on the web whiteboard page and then go through the solutions for the students.

ASSESSMENT FOR LEARNING AND CONCLUSION (10 MINUTES)

The key ideas from today would be re-emphasised. For example the teacher could once again ask 'what is a quantity?' or 'can you quickly give me some examples of quantities.' The teacher could then write up one or two questions on the board for students to quickly complete (AFL). The solutions would then be provided. For homework students would be instructed to complete the questions from their textbook that they could not complete in class.

LESSON EVALUATION QUESTIONS

Did "Web Whiteboard" work well in class?

Are students familiar with what a quantity is?