Susie,
I found the book here: https://annabelleandaiden.com/product/how-we-found-the-earth-is-round/.
The interview with the author here gives a sense of the book.
The Eratosthenes experiment gets carried out each year – you can find an archive of past measurements here: https://eratosthenes.eu/wordpress/. For a senior class or second level!
Time zones are tricky for most people to get their heads around – I’m sure most of us have been woken up by a family member in another country getting the time wrong!