Allie Riordan, 4, center, with mom Amy, learns something surprising during the “States of Matter” program at the Dunwoody Public Library on July 22. The Georgia State University’s Bio-Bus, a mobile laboratory, brought its “States of Matter” program to the Dunwoody Public Library on July 22, so kids could learn about solids, liquids and gases.

Instructor Bazla Shahzad pours a gassy mix.

Solomon Raggs, 5, watches a polymer experiment expand.

Bennett Billeri, 5, Austin Lay, 8, Joseph Makcey, 7, and Joshua Metzger, 9, ask questions.