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Breadboard Connectivity Explorer

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About This MicroSim

A breadboard lets you build circuits without soldering. Hidden under the plastic are metal strips, and every hole touching the same strip is electrically connected. Knowing which holes share a strip is the single most important breadboard skill: most "my circuit doesn't work" problems are a wire one hole off.

This half-size board has:

  • 30 numbered columns. In each column, rows a-e share one strip and rows f-j share another.
  • A center channel that separates the two halves, so a chip can straddle it without shorting its pins.
  • Two power rails along each long edge, marked + (red) and − (blue). Each rail is one long strip that runs the length of the board.

Hover over any hole and every hole connected to it turns gold. Click two holes to add a green jumper wire and see how it joins two strips into one. Check X-ray view to see the metal strips themselves.

How to Use

  • Hover over a hole. The holes it is connected to turn gold, and the line under the title says how many.
  • Click one hole, then another, to add a jumper wire between them. The message tells you whether the wire created a new connection or joined holes that were already connected. Click the same hole twice to cancel.
  • Check X-ray view to show the hidden metal strips.
  • Press Clear jumpers to remove all wires.
  • Press Challenge to be quizzed. Two holes are marked A and B (sometimes with a jumper already placed). Press Yes or No, read the explanation, then press Next question. Press Free play to leave Challenge mode.

Iframe Embed Code

You can add this MicroSim to any web page by adding this to your HTML:

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<iframe src="https://dmccreary.github.io/clocks-and-watches/sims/breadboard-connectivity/main.html"
        height="542px"
        width="100%"
        scrolling="no"></iframe>

Lesson Plan

Learning Objectives

By the end of this activity, students will be able to:

  • Analyze which holes on a breadboard are electrically connected.
  • Explain why the center channel and the separate + and − rails matter.
  • Predict how a jumper wire changes which holes are connected.

Grade Level

9-12 (Clocks and Watches with AI)

Duration

10-15 minutes

Prerequisites

  • Read the Breadboard section of Chapter 2.

Activities

  1. Explore (4 min): Students hover over holes in rows a, e, f, and j of the same column and describe the pattern. Then turn on X-ray view to confirm.
  2. Jumper puzzle (4 min): Ask students to connect hole a3 to hole j20 using as few jumpers as possible. (One jumper is enough, from any of a3-e3 to any of f20-j20.)
  3. Spot the useless wire (2 min): Students add a jumper between c7 and e7 and read the message. Why does it do nothing?
  4. Challenge (5 min): Students answer ten Challenge questions and record their score. Discuss any question type that tricked them.

Assessment

  • Students score at least 8 out of 10 in Challenge mode.
  • Students can state which holes are connected to any given hole without the MicroSim.
  • Students explain why connecting the + rail directly to the − rail is dangerous.

References

  1. Breadboard (Wikipedia) - History and layout of solderless breadboards.
  2. How to Use a Breadboard (SparkFun) - Photos of the metal strips inside a breadboard.
  3. Short circuit (Wikipedia) - Why joining the power rails directly is a problem.
  4. Dual in-line package (Wikipedia) - Why chips straddle the center channel.