DSE ICT | Algorithms and Flowcharts: Tutor Lesson Plan

2026-11-04

Tutor lesson-prep guides · Secondary ICT

Two failures account for most lost marks: a decision diamond with one exit, and a loop count that is one too many. A trace table turns both into the same habit.

Objectives — Students can: (1) use the 5 standard symbols correctly; (2) fill a trace table line by line; (3) show that 6 iterations take 15 steps and 7 condition tests.

01 Prerequisites (3-minute check)

If any of these fails, fix it before the lesson starts.

Skill	Quick check	Pass mark
Variables	Variable versus assignment	Assignment overwrites
Conditions	if versus while	while repeats
Input and output	Symbols for input and output	Parallelogram

02 Lesson flow (60 minutes)

Time	Stage	Tutor does	Student does
0-8 min	Diagnosis	Match four symbols	State the purpose
8-22 min	Five symbols	Terminator, process, decision, I/O, connector	Draw one complete chart
22-36 min	Trace table	One row per executed line	Fill the table
36-48 min	Loop counts	Init, condition, update	Count steps aloud
48-56 min	Question drill	Spot the error, fill the gap	Answer in steps
56-60 min	Exit check	Three quick items	Spoken answers

03 Teaching script (read it out)

Scene 1: Act 1: Five symbols, one mistake costs a mark

The 5 standard symbols are oval, rectangle, diamond, parallelogram and connector circle. Every decision diamond needs two exits, labelled yes and no.
Students do: draw a chart that inputs two numbers and outputs the larger, then count the diamonds.
Common slip: a decision drawn as a rectangle, leaving no labelled exits.

Tutor move: peer-mark symbol by symbol, circling the wrong shape only.

Scene 2: Act 2: A trace table is cheap insurance

Columns: line, condition, variable values, output. Write one row per executed line and never skip.
Students do: fill a 12-cell trace table for a running total.
Common slip: recording the updated value on the row before the test, which shifts every answer by one.

Tutor move: one number per cell; two numbers means a skipped line.

Scene 3: Act 3: Count the tests, not the body

For 6 iterations: one initialisation, two steps per pass (test and update), and one final failing test, giving 15 steps, 7 tests and a body run 6 times.
Students do: write the three numbers beside the chart and check each other.
Rule: tests equal iterations plus one, because the last test fails.

Tutor move: hand-count with n equal to two before trusting the formula.

04 Question types and worked steps

Type	Example	Steps
Draw the flowchart	List steps, pick symbols, label exits, check both branches	Two exits per diamond
Trace table	One row per line, record all variables	No skipped rows
Count iterations	Identify init, test, update, count tests	Tests equal iterations plus one
Spot the error	Check symbols, branches, update	One fault per item

Sanity check (teach this): There are 5 symbols, not four or six. For 6 iterations the path is 15 steps and the condition is tested 7 times because the final test fails; the trace table has 12 cells. Any answer claiming the body runs 7 times is wrong.

05 Independent practice (3 questions)

Question	Answer	What to watch
Number of standard symbols	5	Count the shapes
Steps for 6 iterations	15	One init plus two per pass
Condition tests for 6 iterations	7	Iterations plus one

06 Common mistakes and what to say

Mistake	Student writes	Say this
Diamond with one exit	Only the true branch drawn	“Where does false go?”
Body counted as tests	Answering seven loops	“How many times did the body run?”
Two changes in one row	Skipping a line in the trace	“Which line changed the variable?”
Wrong shapes	Decision inside a rectangle	“Does this shape have two exits?”

07 Homework (paper, section and question numbers)

Flowchart drawing set (in-house) — Questions 1-4: symbols and branches
Trace table practice (in-house) — Questions 5-7: loops and counters

08 Exit check (last 5 minutes)

Question	Answer	Decision
Exits on a decision symbol	Two	Wrong: reteach branching
Tests for 6 iterations	7	Wrong: reteach the plus one rule
Symbol for input	Parallelogram	Wrong: reteach the five symbols

09 Tutor FAQ

Must a flowchart end with a terminator

Yes, an unterminated chart is marked incomplete.

Can a loop be written as repeat-until

Yes, but the test comes after the body, so counts differ by one.

Why keep a trace table in the exam

It turns a logic question into arithmetic the marker can follow.

Find a tutor — free Tutor Registration →

A TutorZone lesson-prep guide. Written by the TutorZone team; questions and lesson flow are original and are not taken from any school or publisher material.