On their website
In addition to the above info tickets are usually $20 but on the weekends you can get the combo ticket (2D film+museum) for around $6.95/ea this includes a stroll through the beautiful forest in the back. Thank me later. ;)
Online at https://fernbankmuseum.org or at the main entrance. At this time they are encouraging to buy tickets online, you just show your e-ticket at the entrance.
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