No apologies for returning to Nasa, one of the first popular educational websites, and still evolving. The Search for Ubar is one of several archaeological projects featured in Nasa’s “observatorium”, an area dedicated to the history, science and art of looking at the world from high altitudes.

It explains how remote sensing from space helped solve one of the great mysteries of Middle Eastern archaeology: the location of the legendary city of Ubar which for thousands of years had been buried under the southern Arabian desert.

The story of the search unfolds over half a dozen pages. Not much depth, but plenty of stimulus for further exploration. In typical Nasa style, there are quizzes and games, plenty of links and a set of teacher’s notes.

The National Trust Environment and Conservation Web Site. www.ntenvironment.com.

The National Trust website has long been a great resource for teachers, and this new venture, looks at how the UK’s largest non-government landowner looks after its 240,000 hectares of countryside, 575 miles of coastline and 40,000 archaeological sites, and the flora and fauna they support.

This is essentially an online library containing policy documents, learned papers, and articles covering a vast range of environmental issues, from a detailed consideration of “green” building materials, to establishing good relations with traveller communities on the Trust’s properties.