1. First, let’s understand what canon is. To simply understand, it means imitation, where one voice imitates another voice.

Listen to Xi Xinghai's "Defend the Yellow River". The second and third "round singing" are the "Canon" technique.

2. From "singing" to "playing", it is easy to understand. The piano cannot sing in turn, it can only play in turn. This partial rotation technique is commonly used in Bach's creative compositions.