Tasks | Early Adolescence | Investigating Order of Operations

Tasks - Year 8, 9

Investigating Order of Operations   by Thelma Perso, Senior Curriculum Officer, Mathematics

Phase of Development:   Early Adolescence

Learning Area/s:	Mathematics
Strand/s	Substrand/s
Number	Calculate Understand Operations
Working Mathematically	Mathematical Strategies Reason Mathematically Apply and Verify
Brief Description:	Students investigate the rule of order using a graphics calculator.
Expected Outcomes:	Students understand the order of operations. Students use a graphics calculator.
Context:	I have used this activity with year 8 and 9 students.
Learning Activities/ Experience:	The Graphics Calculator is a powerful tool for teaching the Order of Operations. Students can view both the operation used and the solution obtained simultaneously on their screen and make conjectures about what they see happening. I suggest students work in pairs so that they can discuss their reasons and verify accordingly.
Resources:	Graphic Calculators Worksheet per student.

Worksheet

Investigating Order of Operations

1. Use you graphics calculator to investigate the solutions to these problems.

3 + 4 x 2	3 + (4 X 2)	(3 + 4) x 2	12 - 3 x 2	(12 - 3) x 2

2. What seems to be happening here? What are the brackets doing?

3. Test your theory with these - do them without a calculator first and then check with your calculator.

5 + 6 x 2	5 + (6 x 2)	(5 + 6) x 2	3 + 4 x 7	(3 + 4) x 7

4. Write about what you have discovered after comparing results with your neighbour.

5. What happens if no brackets are used? Investigate these.

6 + 5 x 2	7 - 3 x 2	8 + 7 x 3	12 - 3 x 3	9 + 2 x 3

6. What do you notice ?

7. Now try these without using a calculator. Check them with your neighbour first and then with a calculator.

4 + 2 x 3	8 + 7 x 2	12 - 6 x 2	14 + 2 x 5	9 - 4 x 2