The Life Starter
Sign up
All courses/Digital

Course 132 · Digital course 27

Understand Circuits with a Free Simulator

Build virtual DC circuits, use meters, predict series and parallel behavior, and diagnose a fault.

Before you start

Use a current desktop browser and PhET Circuit Construction Kit: DC; no account or physical electrical kit is needed.

See everything you’ll need

Practice materials and a worked example · Free download. Download the starter pack

What you’ll leave with

A simulation test report with labeled circuits, predictions, meter readings and an explained fault repair.

Start course Start without an account. Sign in to save lesson progress across devices.

Your project

Start with the practice files. Build your project one lesson at a time.

Practice files are free without an account. Sign in to save your project record in My Proof: a description, checklist, and optional work link. Keep the original files in your own app or notebook; saving a project record does not upload them.

  1. Get your materialsDownload practice filesStart with the supplied materials, follow the lessons, and compare your work with the annotated example.
  2. Make your projectView the project checklist Work in your own notebook, document, or software. Use the supplied practice examples when you prefer.
  3. Keep a private recordSave a project record Sign in to save a description and checklist, then return to update them.
Optional course overview

Watch an introduction.

This overview from Step by Step Science introduces ideas you’ll practice in the lessons.

Watch directly on YouTube
Step by Step ScienceBuilding Series & Parallel Circuits with PhET SimulationsYouTube
Course handbook

Know the route before you begin.

Here’s what you’ll need and what you’ll make. You can return to this guide during any lesson.

Who this is for

Learners ages 14+ who want practical creative and technical skills.

Prepare before lesson one
  • Use a current desktop browser and PhET Circuit Construction Kit: DC; no account or physical electrical kit is needed.
  • Be comfortable dividing decimals; all formulas are introduced in the course. Setup/video time is additional.
Your final project

Finish with proof you can use.

A simulation test report with labeled circuits, predictions, meter readings and an explained fault repair.

Save a project record in My Proof
See project checklist and review criteria

Keep your working files in your own notebook or software. Save a private description, checklist, and work link in My Proof.

What to include

  • Three labeled circuit configurations with voltage, resistance and current units.
  • Predicted and observed measurements with meter positions recorded.
  • A series voltage-sum and parallel current-sum check.
  • One open-branch fault with a single-change test and results.
  • A report distinguishing simulation from physical measurement.

Review and revise

Use these criteria to check your work and choose what to improve.

  • Connections match the intended series or parallel network.
  • Arithmetic, signs and units are consistent.
  • Fault diagnosis is supported by before/after evidence.
  • The report states settings and model limits.
Three ideas to help you along the way
Three useful ideas

The rules behind the steps.

01

Predict first

Write an expected reading before testing.

02

Trace connections

Network behavior depends on paths and nodes.

03

Change one variable

A controlled change produces interpretable evidence.

What do these words mean?
Key words

Key terms worth knowing.

Voltage
Potential difference between two points, measured in volts.
Current
Rate of charge flow, measured in amperes.
Resistance
Opposition to current, measured in ohms.
Series
Components connected in one shared path.
Parallel
Branches connected across the same two nodes.
Your route

6 lessons.
One useful project.

Work in order the first time. Each lesson makes something the next lesson can use.

  1. 1
    Up next

    Build a circuit in a simulator

    Make a complete battery–resistor loop and recognize an open path.

  2. 2
    36 min

    Measure instead of guessing

    Read voltage across a resistor and current in the loop.

  3. 3
    36 min

    Compare two resistors in series

    Predict and measure one shared current and two voltage drops.

  4. 4
    41 min

    Compare parallel branches

    Predict branch currents and check their sum.

  5. 5
    36 min

    Diagnose a mismatch systematically

    Use a predicted-versus-observed record to identify a single fault.

  6. 6
    31 min

    Create a circuit test report

    Explain circuit behavior with checked values and limits.

Use the tools

Tools to help you practice.

See all tools
ZIP · practice files

Understand Circuits with a Free Simulator practice files

Start with the supplied materials, follow the lessons, and compare your work with the annotated example.

Text worksheet

Your course project worksheet

A downloadable text worksheet with each lesson’s working output, space for your answers, and the shared final-project checklist. Save your own copy.

Source transparency

Sources and further study.

Explore the references behind the lessons and take your learning further. Source notes explain access and reuse.

OpenStax: Ohm’s Law
Source & access notes · checked 2026-09-12

Read substantive page text and examples.

Access: Public reading without a paid account; reviewed September 12, 2026.

Reuse: Link only. Lessons and practice assets are original; free access does not grant permission to copy the provider's material.

OpenStax: Resistors in Series and Parallel
Source & access notes · checked 2026-09-12

Read substantive page text and examples.

Access: Public reading without a paid account; reviewed September 12, 2026.

Reuse: Link only. Lessons and practice assets are original; free access does not grant permission to copy the provider's material.

OpenStax: Electrical Measuring Instruments
Source & access notes · checked 2026-09-12

Read substantive page text and examples.

Access: Public reading without a paid account; reviewed September 12, 2026.

Reuse: Link only. Lessons and practice assets are original; free access does not grant permission to copy the provider's material.

PhET: Circuit Construction Kit DC
Source & access notes · checked 2026-09-12

Simulation landing shell and indexed component/measurement descriptions inspected; interactive execution not tested.

Access: Public reading without a paid account; reviewed September 12, 2026.

Reuse: Link to the hosted simulation; do not redistribute or embed the simulation without checking current PhET terms. Original diagrams and numerical fixtures supplied.

Ready when you are

Start with the first useful move.

You’ll always know what to do, what to make, and where to go next.

Start lesson one