ϟlittle spark.ARDUINO LAB
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✦ LESSON 01 / YOUR FIRST CIRCUIT

Blink an LED.

Follow the steps, connect the parts, and test your code.

✳
Beginner7 steps · 10 minutes
WORKSPACE
YOUR WORKBENCH
Setting out your workbench…
FIG. 01ARDUINO UNO R3
DRAG TO TURN · SCROLL TO ZOOM
How to move the 3D view
IN YOUR KIT
</> GUIDED CODE EDITOR
Changes both wait instructions below. 

                

                  ↙Read the loop.
                  

                    Turn the light on.
Wait.
Turn it off.
Do it
                    all again.
                  

                  REPEAT
                

              

              

                Ready when you are. We’ll test your circuit in step 7.
              

            

            

              
THE BIG LITTLE IDEA

              
∞

              
You’re telling electricity
where to go.

              
And when it gets to your LED…
hello, light!

              

                EXPLORE → BUILD → MAKE IT REAL
              

            

          

        

        

          Little Spark · Arduino lessons
        

      

      
      
        
        
USB UPLOAD

        
Upload to your Uno

        

          With a grown-up, connect a
          classic Arduino Uno R3 (ATmega328P) using its USB
          cable.
        

        

          

            1
            

              Build the circuit with USB unplugged. Ask a grown-up to check the
              LED, 220 Ω resistor, and wires.
            

          

          

            2
            

              Run the virtual test in step 7. We test the same compiled program
              that goes to your board.
            

          

          

            3
            

              Plug in USB, connect, then send the program. This needs a desktop
              browser with Web Serial, such as Chrome or Edge.
            

          

        

        
        

        
        

          Safari can run every lesson and the simulator. For USB upload in
          Safari, download the sketch and open it in the Arduino IDE.
        

        

          
        

        

          The virtual test checks program behavior. It cannot inspect the wires
          on your real board. This lesson doesn’t support Uno R4, Nano, or
          ESP32.
        

      
      
        
        
FOR PARENTS

        
Before you start

        

          This first lesson uses a classic Uno R3, a breadboard, a standard LED,
          a 220 Ω resistor, and two jumper wires.
        

        

          Follow each animated step with the board unplugged. Check the LED’s
          long leg connects through the resistor to D13, and its short leg
          connects to GND. Use USB power for this activity.
        

        

          The browser runs the actual precompiled AVR program in an emulator.
          After the test passes, the identical firmware can be uploaded using
          Web Serial and the Uno’s bootloader. Physical uploads still need a
          hands-on check.
        

        

          Guest progress stays in this browser. Signed-in child profiles sync
          progress to their parent-managed account. There are no ads or tracking
          scripts. The editor uses guided timing controls.