At this level students build on their knowledge of designing algorithms from (VCMNA221) by
using a simple general purpose programming language to solve problems. Previously
students may have represented algorithms (a set of logical instructions for carrying out a task)
as a flowchart or diagram. At this level programming language is introduced that allows
students to communicate and write instructions for computers. There are many different
programming languages used such as Java, Python and C as well as many others.
As an introduction to
programming language
students can write in
‘pseudo code’.
Pseudo code cannot be
read by a computer but
will allow students to
check their algorithms
easily before converting it
into a programming
language that a computer
can understand. There is
no set notation that must
be used for pseudo code
however there are terms
that are widely used.
END
Students are also introduced to loops in programming language.
A loop is the steps that are repeated a number of times in an algorithm. Loops assist in
algorithms as they reduce the need for unnecessary steps.
Eg List the steps for eating dinner
1. Place food onto the plate
2. Take plate over to table and sit down
3. Pick up knife and fork.
4. Use knife and fork to cut and grab food.
5. Lift fork to mouth and empty the food from the fork into mouth.
6. Eat mouthful of food.
7. Pick up knife and fork.
8. Use knife and fork to cut and grab food.
9. Lift fork to mouth and empty the food from the fork into mouth.
10. Eat mouthful of food etc...…
Rather than writing out these instructions again and again, a loop can assist and make the
algorithm shorter and easier to read. When using loops in pseudo code the notation WHILE
is used to specify the condition and how many times the loop will repeat.
Eg List the steps for eating dinner
1. Place food onto the plate
2. Take plate over to table and sit down
3. WHILE there is food on the plate
4. Pick up knife and fork.
5. Use knife and fork to cut and grab food.
6. Lift fork to mouth and empty the food from the fork into mouth.
7. Eat mouthful of food.
END
Using an example such as this supports student understanding of how specific they need
to be when writing programming language. Highlight the need to describe every step as this
will be necessary when entering code into a computer. Asking students to write their own
pseudo code for an algorithm and then swapping with another student to see if the desired
output can be achieved from their code is a helpful way of assisting students to see if
enough detail is being provided.
Victorian Curriculum
Design and implement mathematical algorithms using a simple
general purpose programming language (VCMNA254)
VCAA Sample Program: A set of sample programs covering the Victorian Curriculum Mathematics.
VCAA Mathematics glossary: A glossary compiled from subject-specific terminology found within the content descriptions of the Victorian Curriculum Mathematics.
Achievement standards
Students solve problems involving the order, addition and subtraction of integers. They make the connections between whole numbers and index notation and the relationship between perfect squares and square roots. They solve problems involving all four operations with fractions, decimals, percentages and their equivalences, and express fractions in their simplest form.
Students compare the cost of items to make financial decisions, with and without the use of digital technology. They make simple estimates to judge the reasonableness of results.
Students use variables to represent arbitrary numbers and connect the laws and properties of number to algebra and substitute numbers into algebraic expressions. They assign ordered pairs to given points on the Cartesian plane and interpret and analyse graphs of relations from real data.
Students develop simple linear models for situations, make predictions based on these models, solve related equations and check their solutions.
This activity is designed to introduce pseudo code and how it can be used to assist writing programming language.
Introduce pseudo code to students. Ask if any students have heard of pseudo code and if yes what they know about it. Discuss what pseudo code is and how it is used to describe a set of instructions that we can easily check before converting codes into programming language that a computer can understand. Introduce common notation used and describe what each one means.
Demonstrate pseudo code with an example. You may like to start with
a flowchart if students are familiar with representing algorithms in
flowcharts and then convert this into pseudo code.
Eg The algorithm finds the difference between two numbers.
OUTPUT = 3 (since a = 5 and b = 2 a - b = 5 – 2 = 3)
Now convert this into pseudo code (pseudo code is written vertically)
Ask students to have a turn writing their own pseudo code for multiplying two numbers (or any other operation). They can assign their own initial values and see if they get their intended output. You may like to ask for volunteers to display their pseudo code and let the class determine what the output is.
This provides an opportunity to discuss what is needed and how specific pseudo code needs to be to reach an output. With one step missing the output may be misunderstood or will not be able to be calculated, so it is important that students take their time to ensure all steps are listed.
Now present another algorithm written in pseudo code to the class that includes a condition.
E.g. START
SET a=12
IF a/4 is even
THEN OUTPUT ‘a is even’
ELSE OUTPUT ‘a is odd’
END IF
END
Ask students to pair up and discuss what the algorithm is instructing them to do and what the output would show. Ask students to write down what each line of the pseudo code means.
As a class see what responses the students decided on.
What will the output be? (a is odd as 12/4 = 3)
How did you reach this conclusion? (Calculate 12/4 and the answer is an odd number)
Were there any steps in the code you didn’t understand? If so, which steps?
Which instruction/s would need to be changed if we wanted a different output? (Change the initial value or change the operation a/4)
To finish off the activity ask students to write a pseudo code with a condition involved. Ask students to swap their code with another student to see if they can produce the desired output from their pseudo code.
This activity is designed to highlight the benefit of using loops when
there is a series of repetitive instructions.
Begin the lesson with an example that has a series of repetitive
instructions (seeing example in teaching context – eating dinner).
Ask students what might be challenging if we represented these
instructions using pseudocode (students will hopefully identify that it
will be a lot of repetition).
Introduce loops to the class. Loops are steps that are repeated a
number of times in an algorithm. Loops assist in algorithms as they
reduce the need for unnecessary steps.
Refer to the example you used at the beginning of the lesson
(reference made to teaching context – eating dinner). Show how it
could be rewritten using the notation for loops (WHILE) and discuss
how using this notation will make repetitive instructions easier to write
in code
Brainstorm other examples that have a series of repetitive instructions
that would benefit from using a loop. For instance, a dance sequence,
colouring in a picture or counting by the same interval.
Advise students that they will be learning a simple dance today.
Ask them to spread out across the room. Provide students the dance
instructions: have them on the whiteboard or screen for all students
to see. Ask students to try the dance moves slowly at first and then
speed up as they get familiar with the steps.
Clap, Clap, Clap
Hands behind head, Hands on waist, Hands behind head, hands
on waist
Clap, Clap, Clap
Pat head, touch toes,
Pat head, touch toes
Clap, Clap, Clap
Clap, Clap, Clap
Hands behind head, Hands on waist, Hands behind head, hands
on waist
Clap, Clap, Clap
Pat head, touch toes, Pat head, touch toes
Clap, Clap, Clap
Hands on shoulders
Once the students have run through the dance several times ask
students to sit back down and discuss the dance steps
Did you notice a loop or loops in the instructions?
Where would a loop be of assistance?
Would we be able to rewrite the instructions using loops? What
would this look like?
Would we be able to use the same loop for the different dance
moves? Why/why not?
Ask students in pairs to rewrite the dance instructions using loops
where appropriate. If time permits discuss where loops can be added
and how the instructions can be rewritten otherwise, you may like to
collect the revised instructions for assessment.
This teaching idea is taken from the Getting Loopy activity found on
code.org.
This activity is designed to show students how loops can be written in
algorithms using pseudo code.
Revise loops and how they are used in algorithms when a series of
instructions need to be repeated. In pseudocode, the notation WHILE
is used to indicate a condition that is repeated a certain number of
times.
Show the class an example of a loop written in pseudo code (shown
on left-hand side). Discuss with the class what each line means
(shown on the right-hand side)
START
Start
SET c = 3
Assign the initial value as 3
WHILE c <= 6 repeat the next step
While c has a value less than 6 repeat the next step
c= c+1
Add 1 to the value of c
END WHILE
Stop when c is no longer less than 6
OUTPUT c
Write the final value of c
END
End
What will the output be?
Where is the loop?
After the 3rd loop the value is equal to 6 therefore we have repeated the loop too many times. We needed to stop after the 2nd loop.
Therefore, the output is 5.
Here the loop sets a condition and tells us to repeat twice to achieve
our output value.
Provide students with another example and ask them to explain the
meaning of each line. Answers are shown in red.
What is the output?
Where is the loop?
Output = sum = 11 (Note: 4th loop d is larger than 8 so we stop at
the 3rd loop)
Now explain the task to students. They are going to use loops to
write different pseudo codes to represent different algorithms and then create their own algorithms. Some ideas are listed but you may wish
to use others. The examples are designed so that students select
their own variables.
Pair up with another student.
Part 1: Write pseudo codes to represent the following algorithms
Start at 1 and add 1 until the initial value is greater than 5.
Start at 2, keep multiplying by 2 until the number is greater than 30
Part 2: Create two pseudo codes to represent two different algorithms.
You must include a loop in each algorithm. When you are finished
swap Part 2 with another pair and determine what the output is for
each pseudo code. Compare your answer with the other pair and
determine whether you found the right output.
Each pair can then answer these questions underneath where they
have written their algorithms for Part 2.
What did we learn from this activity?
Did our pseudocode assist the other pair to determine the desired
output?
If not, have you identified how the pseudocode can be amended?
