SHS2 Physics · Semester 2 Week 12: Digital Electronics

Lesson notes

Learning Objectives

Indicator: 2.3.3.LI.2 - Distinguish between pull-up and pull-down resistors.

By the end of the lesson, learners can:

Define a pull-up resistor and a pull-down resistor in their own words, stating what each does to a digital input pin.
Identify pull-up and pull-down resistors in a circuit diagram, noting their position relative to the input pin and the voltage source (VCC or GND).
Predict the logic state (HIGH or LOW) of a digital input when a switch is open and when it is closed, for both pull-up and pull-down configurations.
Explain at least two practical applications of pull-up and pull-down resistors in digital circuits, such as in switches, sensors, or microcontroller inputs.
Build and test a simple circuit on a breadboard (or in a simulator) that uses a pull-up resistor with a push button, and one that uses a pull-down resistor, recording the observed input states.

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Curriculum details

Strand: Electric Field, Magnetic Field and Electronics (Strand 3)
Sub-strand: Digital Electronics (3.3)
Content standard: 2.3.3.CS.1 - Demonstrate and understanding of the basics of Digital Electronics. 2.3.3.LO.1 Distinguishing between digital and analogue signals and how digital systems work.
Indicator: 2.3.3.LI.2 - Distinguish between pull up and pull-down resistors.
Suggested placement: Semester 2, Week 12 (Week 32 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 135

Exemplars (from the NaCCA curriculum)

Experiential Learning: Using videos or an experimental set up, differentiate between pull up and pull-down resistors and describe their applications.
Ensure that the teaching materials, examples, and illustrations reflect diverse perspectives.
Assessment (2.3.3.AS.2). The document marks these depth-of-knowledge levels for this indicator: Level 1 Recall; Level 2 Skills of conceptual understanding; Level 3 Strategic reasoning.
Teaching and Learning Resources:
- ICT
- Use of simulation laboratories
- Use of science sets
- Use of oscilloscope
- Basic soldering