Final answer:
In Scratch, you can change the stage's appearance by switching to a different background using the 'backdrop' block.
Step-by-step explanation:
In Scratch, you can change the appearance of a stage by switching to a different background. This can be done using the backdrop block in the programming interface.
For example, let's say you have two different backgrounds: 'Background1' and 'Background2'. To switch to 'Background2', you would use the following code:
switch backdrop to [Background2]
This will change the stage's appearance by replacing the current background with 'Background2'.