Take a tram to the VW Glass factory. Right next door to it, in the Grosse Garten, is the Parkeisenbahn, which is a narrow gauge railway uniquely staffed by children, from ticket seller to station master. Only the train driver is an adult. You can buy tickets for single sections of the route, one of which stops right outside the entrance to Dresden Zoo, or you can buy a round trip ticket for only 5€. The complete journey takes around half an hour. An extremely charming and unusual trip and suitable for children of all ages, from 0-110. Trains are steam powered locomotives on certain weekends throughout the year. Check website for details http://www.parkeisenbahn-dresden.de