Why is the ice smooth during ice hockey games?
The ice hockey smoothing machine was invented in 1940 and is used to keep the ice rink smooth periodically between periods in the game.
Below is an instruction that describes a task, paired with an input that provides further context. Write a response that appropriately completes the request.
### Instruction: Why is the ice smooth during ice hockey games?
### Input: 
### Response: The ice hockey smoothing machine was invented in 1940 and is used to keep the ice rink smooth periodically between periods in the game.