Homeschool Guide: These lesson plans are a guide for parents. Content may contain errors — always cross-reference with official exam board specifications.

analogue signals & filters

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4 detailed 50-minute lessons with teaching scripts, worked examples, parent guides, and assessment criteria.

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Lesson Overview

Total Lessons: 4
Tier: Foundation and Higher
Duration: 50 minutes per lesson (200 minutes total)
Exam Boards: AQA, Edexcel, OCR, Eduqas, CCEA

Learning Objectives

Prerequisites

Materials & Equipment

Lesson 1: Introduction: analogue signals & filters

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Write down everything you already know about analogue signals & filters. Then check against the key terms: key terms from analogue signals & filters. Use a mini-whiteboard or paper.

Main Content (35 minutes)

Parent/Teacher Guide:
Before lesson: Read the script below. Pre-teach key vocab: key terms from analogue signals & filters.
If stuck: Re-read the revision notes (link above), then break the content into smaller steps.
Extension: See the Stretch & Challenge ideas in Lesson 4.
Teaching Script (35 mins):
Mins 0-5 - Hook: "Today: analogue signals & filters. By the end you will be able to answer exam questions on it unaided. It connects to the rest of Electronics because the ideas here recur across the spec."
Mins 5-20 - Direct Instruction: Work through the core ideas below one at a time; after each, ask your student to explain it back in their own words.
Mins 20-30 - Guided Practice: Model the worked example together, then let your student attempt the first practice question with guidance.
Mins 30-35 - Independent Practice: 2-3 practice questions from Lesson 3 below, with immediate feedback.
First Look

Start with the revision notes summary, then attempt: explain the key ideas of analogue signals & filters

Plenary (5 minutes)

Check Out

Your student states one thing they learned and one question they still have about analogue signals & filters.

Lesson 2: Core Concepts: analogue signals & filters

Duration: 50 minutes

Starter Activity (5 minutes)

Review Previous Lesson

Quick recap: write 3 key points from Lesson 1 on analogue signals & filters. Check them against the notes below.

Main Content (35 minutes)

Key Fact: An analogue signal varies continuously in amplitude and time; a digital signal has discrete voltage levels.
Key Fact: Frequency response describes how a circuit's gain varies with frequency; it is typically plotted as a Bode diagram.
Key Fact: An RC low-pass filter allows frequencies below the cut-off to pass while attenuating higher frequencies.
Key Fact: An RC high-pass filter allows frequencies above the cut-off to pass while attenuating lower frequencies.
Key Fact: The cut-off frequency (f_c) of an RC filter: f_c = 1/(2πRC); at this frequency the output is −3 dB (0.707 of input).
Key Fact: Above the cut-off, a low-pass filter attenuates at −20 dB/decade (−6 dB/octave) for a first-order RC filter.

Practice (10 minutes)

Q: explain the key ideas of analogue signals & filters

Answer:

Plenary (5 minutes)

Explain Back

Your student teaches the key points back to you without looking. Fill any gaps immediately.

Lesson 3: Application: analogue signals & filters

Duration: 50 minutes

Starter Activity (5 minutes)

Quick Recall

Recall the key terms: key terms from analogue signals & filters. Define each in one sentence.

Main Content (35 minutes)

Parent/Teacher Guide: Let your student attempt each question alone first, then compare with the model answer. Award method marks for correct working even if the final answer is wrong.

Work through the practice questions on the revision notes page for this topic.

Plenary (5 minutes)

Error Review

Review any questions answered incorrectly. Identify whether the error was knowledge, method, or reading the question.

Lesson 4: Exam Practice: analogue signals & filters

Duration: 50 minutes

Starter Activity (5 minutes)

Command Words

Review what these command words require: state (one point), describe (say what happens), explain (say why), compare (both sides), evaluate (judgement).

Main Content (35 minutes)

Extended Answer

Extended question: Full-Mark Response Describe the operation of RC low-pass and high-pass filters, explaining how the cut-off frequency is determined and how signal conditioning prepares signals for further processing. <div class="

An RC low-pass filter consists of a resistor in series with the signal path and a capacitor in parallel to ground; it allows low frequencies to pass while attenuating high frequencies as the capacitor's reactance decreases. An RC high-pass filter has the capacitor in series and the resistor to ground; it blocks low frequencies (where the capacitor's reactance is high) and passes high frequencies. The cut-off frequency for both is f_c = 1/(2πRC), at which the output amplitude falls to 0.707 of the input (−3 dB). Above f_c, a low-pass filter rolls off at −20 dB/decade; below f_c, a high-pass filter rolls off at the same rate. Signal conditioning prepares raw signals for further processing by amplifying weak signals, filtering unwanted noise, level-shifting to match voltage ranges, and impedance matching using buffer amplifiers (voltage followers) to prevent loading. Active filters using op-amps overcome the limitations of passive RC filters by providing gain, eliminating loading effects and enabling sharper roll-off through higher-order designs.

Exam Tips: Always write the cut-off frequency formula f_c = 1/(2πRC) before substituting values. | Convert all units to base SI (Ω, F, Hz) before calculating to avoid powers-of-ten errors. | Remember: at the cut-off frequency, the output voltage is 0.707 × Vin (i.e. −3 dB), not zero. | Distinguish between roll-off rates: first order = −20 dB/decade, second order = −40 dB/decade. | When sketching Bode plots, mark the cut-off frequency clearly and show the −20 dB/decade slope.
Common Errors: ✗ Calculating cut-off frequency as f_c = 1/(RC) without the 2π factor. ✓ The correct formula is f_c = 1/(2πRC); the 2π factor converts angular frequency to Hz. ✗ Thinking the output is zero at the cut-off frequency. ✓ At f_c the output is −3 dB, which is 0.707 of the pass-band value — not zero. ✗ Confusing the roll-off rates of first-order and second-order filters. ✓ First-order roll-off is −20 dB/decade; second-order is −40 dB/decade. ✗ Forgetting to convert component values to base SI units before calculating. ✓ Convert kΩ to Ω, nF to F, µF to F etc. before substituting into f_c = 1/(2πRC).
Stretch & Challenge (Grade 8-9):
  • Synoptic links: explain how analogue signals &amp; filters connects to another Electronics topic you have studied
  • Real-world: research one real-world use or example of analogue signals &amp; filters
  • Critical: "What are the limitations of the models used in analogue signals &amp; filters?"

Plenary (5 minutes)

Assessment Criteria
  • Got it: Confident explanation + correct worked examples
  • Getting there: Main points OK, needs support with detail
  • Not yet: Confused on key concepts - re-run Lesson 2

Homework & Consolidation

Recommended Resources

🎓 Smart Lesson (Guided)