You can take your kids on a boat ride on the Vltava, which seems to be the thing that all Prague families do on sunny summer weekends. A fun activity that can fill your day is to take the boat to or from the Prague Zoo.

Departure point: Rašínovo nábřeží embankment between the Palackého and Jiráskův bridges
Departure times to the zoo: 9:30 a.m., 12:30 p.m., 3:30 p.m.
Departure times from the zoo: 11 a.m., 2 p.m. and 5 p.m.
May 1 - September 13: daily
March 28 - April 30 and Sep. 14 - Nov. 1: Saturdays, Sundays and holidays
Ride duration: 75 minutes
Cost: Adults 140 Kč, children 70 CZK, children under 3 - free
Website: www.paroplavba.cz