If you have young grandkids, here's something to put on your short list for the longest day of the year.

Summer begins next Sunday, June 21, and the Nassau County Museum of Art in Roslyn Harbor is holding a picnic party on the lawn. The day features art-related games, including a sculpture scavenger hunt where kids can build their own tribute to summer. And everyone will be needed to lend a hand to the day's big event: a giant bubble painting. The museum will supply the bubbles and the paint, but you should bring a blanket to sit on and some snacks.

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The cost: adults, $10; children 4-12 and students, $4, seniors 62 and older, $8; plus an $8 per family materials fee.

For more information, visit nassaumuseum.com or call 516-484-9337.