Rather than writing simple definitions of a word, the children are encouraged to write longer pieces centred on a particular word. So if you look up "apfel", for example, you'll et a little passage about the colour of apples, the various types and the author's favourite apple recipes. The work is checked by teachers at the participating schools before being submitted to a central site for publication.
Kinderlexicon is an excellent prototype for schools wanting to combine English and ICT. Not only is it a simple idea, it is a resource that can be built up over time and can easily involve children of varying ages and abilities.