Test a claim about digital information

When does a digital message resist noise, and when does it fail?

Submit: An evidence record, explanation and revision.

Related lesson: Waves and Optics

This is a teacher-led extension beyond the short lesson. The task supplies a performance opportunity; completion alone does not certify mastery, full NGSS coverage or state alignment.

Build the idea

Digital systems represent information with discrete symbols. Thresholding and error-control schemes can help recover a message after some noise, but severe noise can still cause errors. Copying discrete values can avoid cumulative analog degradation; digitization also involves resolution, sampling and storage tradeoffs.

Evidence and model inputs

Original transmission model: send bits 1,0,1 using voltages 5,0,5. Received values 4.2,0.7,3.8 decode using a 2.5 V threshold. A second channel returns 2.0,3.0,4.0. Optional triple repetition sends each bit three times and uses a majority vote, increasing message length threefold.

Keep actual observations, published findings and invented model cases labeled separately. If a source or required equipment is unavailable, pause that part with a teacher; do not invent results.

Materials and preparation

Paper, graph paper or spreadsheet, and the linked readings.

Grade-level scope

Conceptual and simple numerical coding models; detailed communications circuitry is not required.

Do the work

1. Decode both channels and count errors relative to the original.
2. Create a three-copy code for the message and test one corrupted copy per group.
3. Ask what noise assumptions make thresholding or repetition helpful.
4. Compare storage/transmission cost with reliability; distinguish an analog waveform from its sampled digital representation.
5. Evaluate “digital information never loses quality” using the two cases and a finite-resolution example.

Learner worksheet

Write on paper or type here and print. Entries stay in this page’s memory and are lost when you leave or reload; they are not saved or submitted.

Check your reasoning

1. What does the first channel decode to?
2. What does the second decode to?
3. What can majority voting correct here?
4. Is threefold repetition free?

Teacher review guide

Review the actual deliverable and discuss the reasoning. For each criterion, use 0 when evidence is absent or fundamentally incorrect, 1 when partly supported with a material error or omission, and 2 when accurate, supported and complete for the stated task. Maximum 8 points is a task score, not a proficiency certification. Give feedback and allow revision.

1. Decodes messages and measures errors correctly.
2. Asks useful questions about noise and recovery.
3. Evaluates a digital advantage with a counterexample.
4. Explains reliability, sampling or storage tradeoffs.

Sources and standard reference

• Official NGSS HS-PS4-2 performance expectation — inspect the practice, core idea, crosscutting concept and assessment boundary.

Instructional text and hypothetical cases are original. Linked source readings supply published evidence where specified. Teachers should judge fit with their course and state requirements.