Here is a great warmer for any level.
All I did was open my iPad, type "thought for the day (images)" and ask my student to choose one or two that appealed to her.
"If you're in your comfort zone, you're not really alive."
"If you can't explain something in simple terms, you don't really understand it." (Einstein)
Then we had an interesting discussion that went far beyond the two sayings.
This is a fantastically easy and stimulating warmer! Highly recommended!