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Why isn't the simulator showing up in MakeCode?

If you've plugged in your solar component and the on-screen version of it never appears in MakeCode, you're almost certainly missing one of three things. The simulators only show up when all of these are true:

  1. The Forward Education extension has been added to your MakeCode project.
  2. Your micro:bit is paired with MakeCode.
  3. Code that uses the extension has been downloaded onto the micro:bit.

Step 3 is the one most people miss. Adding the extension and pairing isn't enough on its own — the micro:bit has to actually be running a program that includes Forward Education blocks before it can report which components are plugged in.

"Simulators" are the live, on-screen versions of your real sensors and motors. When they're working, covering the solar sensor with your hand makes the value on screen drop in real time.

Before you start

  • Use a laptop or desktop with a Chromium-based browser (Chrome or Edge). Pairing uses WebUSB, which isn't available in every browser. See Compatible Devices and Browsers for Forward Education Products and micro:bit in this help centre.
  • Use a v2 micro:bit, seated firmly in the edge connector of the Breakout Board (the board your micro:bit slots into, that all the components plug into).
  • Turn the Breakout Board on.
  • Make sure your USB cable is a data cable, not a charge-only cable.

Step 1 — Add the Forward Education extension

  1. Open a project at makecode.microbit.org.
  2. Scroll to the bottom of the block drawers and click Extensions.
  3. Search for forward, Forward Education, or fwd-edu and select the Forward Education extension.
  4. Two new drawers appear: Sensors and Motors. (Introduction to MakeCode Simulators)

If you don't see those two drawers, the extension didn't load — reload the page and try again.

Step 2 — Pair your micro:bit

  1. Plug the micro:bit into your computer with the USB cable.
  2. In MakeCode, click the … (three dots) beside the Download button and choose Connect Device.
  3. Follow the prompts and select your micro:bit in the browser's device list.

See Pairing your micro:bit in MakeCode and the Walkthrough – pairing your micro:bit article, or the micro:bit Pairing & Simulators lesson on the Learning Platform.

Step 3 — Download your code to the micro:bit

This is the step that fixes most "my solar simulator isn't appearing" cases.

  1. Drag at least one Forward Education block (from Sensors or Motors) into your program — for example, a solar sensor reading block.
  2. Click Download.
  3. Wait for the transfer to finish and for the micro:bit to restart.

Once that program is running, MakeCode can see the components attached to the Breakout Board, and the solar simulator should appear in the simulator area. From then on, you can plug and unplug components and the on-screen versions update automatically — no need to power-cycle the board each time.

To test it, cover the solar sensor with your hand: the percentage on screen should drop.

Still nothing? Try this reset

If the micro:bit seems stalled:

  1. Unplug the USB cable.
  2. Turn the Breakout Board off.
  3. Slide the micro:bit out of the Breakout Board.
  4. Put it all back together, turn the board on, plug the USB back in, and re-pair.

This sequence is also covered in the MakeCode Simulators Overview video on the Learning Platform.

Other things worth checking:

  • Try a brand-new MakeCode project and redo steps 1–3, in case the project file is in a bad state.
  • Check that your solar component is fully clicked into a port on the Breakout Board (or into the component it's daisy-chained from).
  • If pairing fails on school devices, your district may need to allow the MakeCode and Forward Education domains — see What domains does my school district need to whitelist?

In the classroom

Pairing happens per computer and per browser. If students move to a different device, log in somewhere else, or the browser is reset overnight, they'll need to re-pair their micro:bit and download their code again before the simulators come back. Building "connect, then download" into your start-of-class routine saves a lot of hands up.

Still stuck?

If you've worked through all of the above and the solar simulator still doesn't appear, contact our team (see How do I contact support?) with your browser, operating system, and a description of which components are plugged in. We can also set up a call if a whole set of kits is affected.