Virtual excursions or field trips can provide similar learning experiences to real visits to zoos and museums, without the expense and organisation - especially if you are in regional and remote locations. Although I don't believe you should replace all camps and excursions with virtual experiences, they offer another way of learning that can engage students. Organisations such as museums and art galleries set up online exhibitions that can be easily accessed from classrooms anywhere in the world if you have an internet connection. You can also make your own trips using resources available on the Internet. The WA Department of Education offers some more ideas for Virtual Tours here.
You can ask students to send you a digital postcard from the place they have visited or create a travel brochure, diary or blog about their journey. "If it were my Home.." is a very interesting site with a comparison tool so that students can compare living conditions with another location and imagine what life might have been like if they were born somewhere else. You can also use their visualization tool to help understand the impact of a disaster. The Pakistan Flood and BP Oil Spill were recently featured.
Africam allows learning about the wildlife in a game reserve in Africa. Cameras in several areas of the reserve allow viewing of the animals. Animals are most likely to be seen during the dry months of April-November. Most activity takes place in early morning and late afternoon. Students can observe the behaviour of animals at the water hole or across the savannah and describe their structural characterisitics. What adaptations do these animals demonstrate?
Boston Museum of Science has on-line virtual tours include a scanning microscope, the universe, electricity, fractals, and featured exhibits.
Chicago Museum of Science and Industry has changing online exhibits as well as more than a dozen permanent displays. Explore the human heart, tour a German U-boat or take a walk through a gem-filled fairy castle.
The San Francisco Exploratorium is the museum of science, art and human perception. Explore solar eclipses, earthquakes, underwater life, plantetary systems and much more.
Hubble Space Telescope is a NASA site with space transmissions, fantastic images from the Hubble telescope and learning activities. They have an Education and Museums page with web-based activities that tackle topics from comets to black holes. Construct a galaxy, plan a NASA mission, learn the history of the telescope and more.
Expedition to the Galapagos Islands from the Smithsonian National Institute of Natural History, has video footage and a photo journal from a 14 week visit during 1998 and 1999, by Doctor Carole Baldwin and her colleagues. They explored the remote islands and surrounding ocean to document the unique wildlife and stark landscape.
Monterey Bay Aquarium has a podcasts, videos and web cam page where you can veiw sea otters, penguins, kelp forests and other ocean animals - it also has interactive games and activities for students. They also have a great video library and a page where your students can create e-cards. You can ask students to visit the aquarium and then write you an e-card about the structural, functional and behavioural adaptations of one of the animals they observe.
National Geographic Critter Cams, such as the Virtual World Arctic allow you to view the world as various species do, by using cameras attached to animals in their natural environment. There is a great range of marine and terrestrial species including whale sharks, humpback whales, seals, sharks, bears, lions and more. This is one of my favourites! Ask students to design a camera that takes into account the behaviour and habitat of an organism - does it need to be waterproof and robust, or light and disposable? How could you film the behaviour of dangerous creatures such as crocodiles and lions?
Reefs of the Gulf offers tours of the Gulf of Mexico aboard a nuclear-powered submarine. Follow the scientists on their research mission and learn about sea turtles and other marine life, light in water and how the scientists detect hydrocarbon seeps. You could ask students to write a report, pretending they were a scientist on the mission, trapped underwater and sending important information about new research discoveries back to their base.

More Virtual Field Trip sites at OOPS. This is an extensive alphabetical list of sites for virtual field trips for all subjects. It also has some teaching ideas, such as creating a travel log, treasure hunt or online scrapbook. The Utah Education Network also has a list of Virtual Field trips for Science organised by themes as well as locations (volcanoes, trees, wetlands, space, wildflowers, tectonic plates).