Lesson 2 - Geekservo: Regular Mixing Keeps Compost Sweet-Smelling
1. Engage: How to turn waste into treasure?
Imagine finishing your apple at lunch and tossing the core in the bin. Where does it go next? Most kitchen waste like fruit peels, vegetable scraps, and bread crusts ends up in landfills. There, it rots without oxygen and releases methane—a gas 25 times more harmful to the climate than CO₂. But what if we could turn that smelly waste into something that helps plants grow super well? That’s called compost, and today we’re going to use tech to make composting easier and more effective!
Key Question
How can we turn kitchen waste into a "super food" for plants, while helping the climate?
Instruct student to have discussion (e.g., bury it in the garden? Use a special bin?).
Reveal: We’ll learn to make compost, then build an automatic stirrer with the micro:bit and Geekservo to keep our compost healthy and sweet-smelling.
2. Explore: What Makes Compost Work?
Compost is made by tiny microbes (like bacteria and fungi) that eat organic waste. These microbes need three key things to do their job well:
Carbon (Browns): Dry materials like dead leaves, newspaper, or straw (gives microbes energy)
Nitrogen (Greens): Fresh waste like fruit peels, coffee grounds, or grass clippings (helps microbes grow)
Oxygen: Air to keep microbes active (without it, compost stinks!)
Activity 1
Prepare plastic balls brown-brown for carbon sources, green for nitrogen sources.
Tell students to pick balls to add to your "compost bin" (a small container).
Record the number of brown vs green balls in a table. Aim for a 3:1 ratio of brown to green (the ideal balance for microbes!).
Now, think about oxygen.
Key Question
How do we get enough air into the compost pile?
If compost doesn’t get enough oxygen, it turns slimy and smells bad. How do we give microbes oxygen? By stirring the pile regularly! But stirring by hand can be tiring. Can we use tech to help? Yes—meet the Geekservo, a small motor that can automatically stir our compost pile for us.
3. Engineer: Build Your Automatic Compost Stirrer
Let’s build a motorized stirrer using the micro:bit and Geekservo:
Make the hardware connections by the following diagram:
Coding Steps (Using MakeCode):
1.Open Microsoft MakeCode through the link below.
https://makecode.microbit.org/
2.Create a new project.
3.Go to Extensions tab to add the extension.
4.Enter the URL: https://github.com/cdjq/pxt-expansion-board-for-microbit-k10 → click it
5.Then add one more extension as follows:
6.Drag the following blocks together to build the code:
Watch your stirrer swing back and forth—your automatic compost helper is ready!
4. Experience & Challenge: Test Your Stirrer
Activity 2
1.Assemble the compost bin following the steps in the Activity Sheet.
2.Program and download the program to micro:bit.
3.Test the stirrer by using the A and B buttons to control the rotation and stop of the compost bin.
Challenge: Simulate Timed Compost Turning
Research shows real compost piles need stirring every 3-7 days to stay healthy. Let’s make a compost bin that can turn and mix automatically at set intervals.
Activity 3
Modify your program to make the stirrer run for 2 seconds, then pause for 5 seconds.
Download the new program to micro:bit.
Watch the automatic timed stirring and note how it keeps the "compost" mixed evenly.
5. Elaborate: Why Compost?
Composting isn’t just about reducing waste—it’s a superpower for our planet:
1.Cuts down on methane from landfills, slowing global warming
2.Feeds soil with nutrients so plants grow strong, supporting bees, butterflies, and birds
3.Reduces the need for chemical fertilizers that harm soil microbes
4.Helps soil hold water, so plants survive dry spells better
This supports SDG 15: Life on Land—ensuring healthy ecosystems for all land creatures.
What can you do at home to help?
1.Start a small countertop bin for fruit peels.
2.Ask your family to turn the garden compost pile weekly.
3.Use compost to feed your houseplants or school garden.
Key Takeaway: With a little tech and simple science, we can turn waste into something amazing for our planet—one compost pile at a time!
Lesson2.zip 
