If you pay in person/at the museum and your NOT a MSI member, the fees are: $21.95 for an adult and $12.95 for kids. If you purchase the tickets on their website: https://tickets.msichicago.org/visitors you will save $2.00 off of each ticket. If you have a paid membership then you know the fees involved if any.
Check the webpage, it depends of the day and alternatives due to special exhibits
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