5.3 Coding & Computational Thinking in Ontario Math

5.3 Coding & Computational Thinking in Ontario Math

With the release of the revised 2020 Ontario Elementary Mathematics Curriculum (Grades 1–8) and the 2021 De-streamed Grade 9 Course (MTH1W), Coding and Computational Thinking were formally integrated into Strand C: Algebra. Knowing what coding looks like in the Ontario program matters for the MPT's pedagogy component: The Program in Mathematics and The Mathematical Processes are named sections of the Mathematics Curriculum Context dimension, and Strand C is where coding lives.

Scope note. Coding and computational thinking are not among EQAO's published fundamental knowledge and skills for the mathematics content component (Number Sense; Relationships and Proportional Reasoning; Measurement). Do not expect to trace pseudo-code for marks in Section 2 or Section 3. Study this section to understand the curriculum you will be asked about, and because tracing an algorithm is excellent practice for the multi-step arithmetic and linear-relations reasoning that the mathematics component genuinely does assess.

---

1. The Four Pillars of Computational Thinking in Math

Computational thinking is a problem-solving process that formulates mathematical tasks so that their solutions can be executed by a computer or systematic algorithm.

Loading diagram...

1. Decomposition: Breaking a complex mathematical problem into smaller, manageable sub-problems (e.g., separating total revenue calculation into calculating individual unit sales and applying discounts).
2. Pattern Recognition: Identifying trends, rules, or repeating structures in data or numerical sequences (e.g., discovering first differences in linear relations).
3. Abstraction: Stripping away non-essential details to focus on general mathematical formulas or algebraic logic (e.g., converting specific numeric steps into a general formula $y = mx + b$).
4. Algorithm Design: Developing a step-by-step, ordered set of instructions (pseudo-code) to solve the problem systematically.

---

2. Core Programming Constructs in Pseudo-code

In Ontario classroom resources, algorithms are usually presented in language-agnostic pseudo-code. Understanding the fundamental control structures is what lets a teacher read, run, and repair student code.

A. Variables & Assignment

• Assignment Operator (SET or <-): Stores a value in a variable.
• Key Distinction: In algebra, $x = x + 1$ is an impossible equation. In programming, SET x = x + 1 takes the current stored value of $x$, adds 1, and overwrites $x$ with the new result.

SET total = 0
SET rate = 15.50
SET hours = 40
SET total = rate * hours

B. Sequential Logic

Instructions execute in exact sequential order from top to bottom, one line at a time.

C. Conditional Control Structures (IF-THEN-ELSE)

Conditionals allow an algorithm to branch and execute different mathematical calculations based on whether a Boolean condition evaluates to TRUE or FALSE.

IF hours > 40 THEN
    SET overtimeHours = hours - 40
    SET pay = (40 * rate) + (overtimeHours * rate * 1.5)
ELSE
    SET pay = hours * rate
END IF

D. Looping Control Structures (Repetition)

Loops allow code blocks to execute repeatedly without duplicating lines.

1. Count-Controlled Loop (FOR Loop): Executes a predetermined number of times.

SET sum = 0
FOR i FROM 1 TO 5 DO
    SET sum = sum + i
END FOR

1. Condition-Controlled Loop (WHILE or REPEAT-UNTIL Loop): Executes continuously as long as a Boolean condition remains true (or until a condition becomes true).

SET balance = 1000
SET month = 0
WHILE balance < 2000 DO
    SET balance = balance * 1.05
    SET month = month + 1
END WHILE

---

3. Systematic Execution Tracing & Trace Tables

To trace pseudo-code accurately during an examination, construct a Trace Table. A trace table tracks line execution step-by-step alongside variable values and condition checks.

Example Trace Walkthrough

Consider the following algorithm designed to accumulate the sum of odd numbers:

Line 1: SET sum = 0
Line 2: FOR k FROM 1 TO 4 DO
Line 3:     SET oddNum = (2 * k) - 1
Line 4:     SET sum = sum + oddNum
Line 5: END FOR
Line 6: PRINT sum

Executed Trace Table:

---

4. Debugging Common Mathematical Algorithm Errors

Debugging—identifying and correcting errors in mathematical algorithms—is an expectation of Strand C in the Ontario curriculum, and knowing the common failure modes helps you reason about the curriculum in pedagogy scenarios.

Common Algorithm Errors

1. Off-by-One Errors: Loop bounds execute one too many or one too few times (e.g., FOR i FROM 1 TO N-1 instead of 1 TO N).
2. Incorrect Initializer Values: Setting accumulators to the wrong starting value.
   • For addition/summation: Initialize to 0 (SET sum = 0).
   • For multiplication/factorials: Initialize to 1 (SET product = 1). Initializing to 0 causes all future products to equal 0.
3. Infinite Loops: Forgetting to update the control variable inside a WHILE loop (e.g., failing to increment counter = counter + 1).
4. Inverted Logic Operators: Using < instead of > or failing to include equality (>=).

---

5. Step-by-Step Worked Examples

Worked Example 1: Execution Trace of a Conditional Loop

Problem: Determine the final printed output of the following pseudo-code algorithm:

SET count = 0
SET total = 50
WHILE total > 15 DO
    IF total MOD 2 == 0 THEN
        SET total = total - 10
    ELSE
        SET total = total - 5
    END IF
    SET count = count + 1
END WHILE
PRINT count

(Note: MOD computes the remainder after integer division).

Solution:

• Iteration 1: total = 50. Condition total > 15 is TRUE. 50 MOD 2 == 0 is TRUE (even). total becomes $50 - 10 = 40$. count becomes $0 + 1 = 1$.

• Iteration 2: total = 40. Condition total > 15 is TRUE. 40 MOD 2 == 0 is TRUE (even). total becomes $40 - 10 = 30$. count becomes $1 + 1 = 2$.

• Iteration 3: total = 30. Condition total > 15 is TRUE. 30 MOD 2 == 0 is TRUE (even). total becomes $30 - 10 = 20$. count becomes $2 + 1 = 3$.

• Iteration 4: total = 20. Condition total > 15 is TRUE. 20 MOD 2 == 0 is TRUE (even). total becomes $20 - 10 = 10$. count becomes $3 + 1 = 4$.

• Loop Termination Check: total = 10. Condition 10 > 15 is FALSE. The loop terminates. Final Printed Value: count = 4.

---

6. Pedagogical Note for Ontario Classrooms

In Ontario schools, teachers connect block-based platforms (such as Scratch or Lynx) to math concepts. For instance, creating scripts to draw regular polygons requires computing interior/exterior angles ($360^{\circ} / n$), directly combining geometry with loop controls.