Every song you love is built from three things you can see, hear and change: pitch, rhythm and harmony. Today you'll take them apart.

In this lesson you'll:

• see how a vibration becomes a sound, and what makes it high or low, loud or soft;
• feel tempo, then build your own beat on a drum machine;
• discover why some notes blend and others clash;
• build scales and chords, and loop the four chords behind many pop songs.

Time: about 50 minutes. You need: headphones or speakers if you can — every block also works silently.

Tap the three pictures above, then move on to the first step.