What can I do at the airport?

I haven't traveled much yet - I'll have to wait four hours between two flights. My cell phone battery is low and I don't want to carry much with me. What can I do while I'm waiting without using my cell phone? And I don't want a power bank either.
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I have written notes with the states and capitals of the USA and am learning a little geography. Like the vocabulary I learned at school. Two books are in my bag but it is not quiet enough for me here
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I was in Greece - so many American tourists at the airports. I had two Stopps, that sucks. Munich & Athena. One the First break I drunk a Cappuccino & ate a piece of cake - 10€. That's why I didn't one more time. Travel is stress and not fun but I am safe home again
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Why do so much American travel now? Not that typical vacation time
What can I do at the airport?
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