Voting Machine Testing

Overview

Students finish their Micro:bit Voting Machine by adding usability features (reset, result announcement animation, and optional sound). They conduct in-class mock elections, record results, and use evidence to decide what must be fixed so the machine is accurate and easy to use.

Learning intentions

Students will be able to:

• Explain what “additive inverses” and “signed movement” mean on a number line in a real context, using examples from vote totals and feedback logic.
• Verify that integer division rules for negative values behave consistently when interpreting “change from baseline” metrics.
• Run test cases, collect data from mock votes, and use the data to improve the voting machine.
• Present their machine, gather peer feedback, and revise based on observed usability issues.

Success criteria

• I can run at least 10 mock votes and report whether each vote was recorded correctly.
• I can describe one usability strength and one improvement using evidence from my test data.
• I can use number-line reasoning to explain how adding the “opposite” of a value returns to 0 in a context related to vote counts or score changes.
• I can interpret how negative “change” values would be handled consistently when calculating differences.

Curriculum links

• Number System — addition and subtraction of rational numbers using horizontal or vertical number lines.
• Number System — subtraction of rational numbers as adding the additive inverse, including distance via absolute value (CCSS.MATH.CONTENT.7.NS.A.1c).
• Number System — integers divided produce rational numbers; sign rules for quotients (CCSS.MATH.CONTENT.7.NS.A.2b).
• Number System — understanding multiplication and rules for signed numbers in extended rational contexts (CCSS.MATH.CONTENT.7.NS.A.2a).

Lesson structure (45 minutes)

1. 0–5 min · Warm-up prompt. Teacher displays a simple voting scenario: “Candidate A got 6 votes, Candidate B got 10 votes. What is the difference?” Students quick-write the difference and then discuss whether the result could be negative depending on how you subtract.

2. 5–12 min · Micro:bit finalization sprint. Teacher shows a 1-slide checklist: reset button, result animation, optional sound, and “confirm display matches internal totals.” Students review their code quickly and fix any missing features using a guided print sheet (beginner) or peer help (advanced).

3. 12–20 min · Test plan demo (data + math link). Teacher models a testing table with columns: Trial #, Vote A, Vote B, Machine output, Check (Correct/Incorrect). Teacher also models one math sentence: “If we define change as (A − B), the ‘opposite’ change is (B − A), and adding them gives 0,” using a number line diagram. Students echo this reasoning verbally with one example from the board.

4. 20–33 min · Mock voting rounds. Students work in groups of 3–5 with one “tester,” one “operator,” and one “recorder” (rotate roles midway). Each group runs 10 quick votes with a predetermined pattern (teacher provides patterns on paper to reduce confusion). Students record whether totals and announced results match the expected counts.

5. 33–40 min · Debug using evidence. Teacher directs students to circle any trials where the machine output mismatched expected results, then brainstorm 1–2 causes (button mapping, debouncing, reset logic, animation timing). Students make one targeted change and rerun 3 additional votes to check improvement.

6. 40–45 min · Peer feedback mini-presentations. Each group presents for about 1 minute to a neighboring group: “What works best? What confused users? What will you change?” The listener group provides one actionable feedback statement using a sentence frame: “We noticed…, so we recommend…”

Resources

• Micro:bit devices and USB cables (or batteries) for charging if needed
• Voting Machine program files or starter templates
• Printed testing data table (Trial #, expected totals, observed totals, result check)
• Step-by-step build guide for beginners (reset + announce + optional sound)
• Challenge prompt cards:
• Add a third candidate and update the result display
• Add a percentage display based on total votes
• Debrief question cards with sentence starters
• Timer/stopwatch
• Teacher display with the checklist and sample testing table

Assessment

• Formative during sprint: quick scan of reset/announce/sound features checklist
• Formative during mock voting: teacher circulates, checks that students are recording expected vs observed results accurately
• Data-based feedback check: students must cite one evidence point (“Trial 4 mismatch”) during peer feedback
• Exit ticket (last 1–2 minutes, collected as a quick paper slip):
• “Write the opposite of (A − B) and explain what happens when you add them.”

Differentiation

• Support for beginners:
• Provide a step-by-step build guide with screenshots of button events and reset logic
• Give structured test patterns so students focus on debugging, not planning
• Offer number-line sentence frames for the math connection (“Adding the opposite returns to 0”)
• Extension for advanced learners:
• Add a third candidate with corresponding display/logic updates
• Add percentage output using total votes, then test with at least 10 trials for accuracy
• Challenge: include a “change from baseline” metric (e.g., comparing current difference to a previous round) and ensure negative values behave as expected
• EAL/SEN:
• Use role cards with icons for tester/operator/recorder
• Provide word banks for feedback (“works,” “confusing,” “doesn’t match,” “fix,” “try again”)
• Allow oral responses to the exit ticket if writing is a barrier