A STEM Project for the School Science Fair: Build a micro:bit Weather Logger

A science fair project lands harder when it shows real measurements instead of a poster of facts. The micro:bit V2 lets a learner build a working weather logger that records actual room conditions over time, and it does it without a single extra sensor module. The temperature sensor, microphone, and speaker are already on the board, so the project is about clever coding and clear data, not soldering a parts list together.

Quick Answer

You can build a complete science fair weather logger using only a micro:bit V2, because the board has a built-in temperature sensor, microphone for sound levels, and a speaker, all ready to log readings. The data exports as a CSV file you open in any spreadsheet to graph, which turns a coding project into a proper data-driven experiment.

What you need before you start

The whole point of this build is how little it asks for. You need a micro:bit V2, a USB cable, and a computer to program it. For logging away from the computer, a battery pack lets the board run on its own on a windowsill or outside a window. That is the full shopping list. Boards like this sit in our smart home and maker components, and a spare cable or battery holder is the kind of small extra worth grabbing at the same time.

Step one: read the onboard sensors

Open the MakeCode editor and start a new project. The micro:bit V2 exposes temperature directly through a single block that returns degrees Celsius from the chip on the board. Sound level comes from the onboard microphone as a number from 0 to 255, which is perfect for tracking how noisy a room gets through the day. Drag those two readings into your loop so the board captures both each time it logs. Test it live first by showing the temperature on the LED grid, so the learner can see the number change when they cup the board in a warm hand.

Step two: log readings with a timestamp

The built-in data logging feature is what makes this a real experiment. Add the logging extension, then write a row every set interval, say every five minutes, capturing time, temperature, and sound level together. Use a forever loop with a pause so the board records on a steady schedule. The running time block gives each row a timestamp, so when you graph the data later you can see exactly how the room warmed up through the morning and cooled in the evening.

Tips for clean data

Mount the board somewhere it will not get knocked, keep it out of direct sun if you want true air temperature, and let it log for at least a full day so the graph tells a story. A longer run, two or three days, gives the learner real patterns to explain at the fair.

Step three: export and graph the CSV

When the logging run is done, plug the micro:bit back into the computer. The logged data downloads as a CSV file straight from the board. Open it in any standard spreadsheet, select your time and temperature columns, and insert a line chart. Suddenly the learner has a graph of how their classroom or bedroom breathes through a day, which is exactly the kind of evidence a science fair judge wants to see. They can add the sound-level line on a second axis to show, for example, how noise spikes during a busy afternoon. For project ideas and supporting bits, the maker and accessory best sellers are a good browse.

Turning data into a winning display

Encourage the learner to write a short hypothesis before logging, such as "the room is coldest just before sunrise," then let the CSV graph prove or disprove it. That structure, predict then measure then explain, is what separates a good fair project from a great one. Printing the graph beside the live board on the display table shows the work behind the result.

Frequently Asked Questions

Does the micro:bit V2 really measure air temperature?

The onboard sensor reads the temperature of the chip, which closely tracks the surrounding air once the board has settled. Keep it out of direct sun and away from a warm device for the most accurate room reading.

How is the V2 different from the original micro:bit for this project?

The V2 adds the built-in microphone and speaker, so sound logging works with no extra parts. The original board can still log temperature but cannot capture sound levels on its own.

What software does a learner need to program it?

The free MakeCode block editor runs in a browser and needs no installation. It uses drag-and-drop blocks, which suits primary and high school learners new to coding.

How long can the logger run on a battery pack?

A couple of AA cells will comfortably run a low-power logging loop for a full day or more, which is plenty for a fair experiment. Longer runs just need fresh cells.

Can the same project log other conditions?

With the onboard sensors alone you get temperature and sound. Adding external modules later can bring humidity or light, but the no-extra-parts version already gives two solid data streams to graph.