``The participants for the Rajkot exhibition will include those who came up with the best models during exhibitions at the zonal, district and state levels,'' said NCERT science department director Dr R D Shukla. ``The Rajkot exhibition will showcase the finest talents at the school level in our country.''

The theme for the exhibition Science, Technology and Environment was announced two years ago and all the schools located in various villages and towns informed about it. There were six sub-themes which the students had to keep in mind while devising their projects. These included Food, Health and Nutrition;Energy, Technology and Environment; Industry and Environmental Protection; Transportation and Communication; and Technological Aids. The participants were asked to let their imagination loose, the only guiding factor being that their projects should be based on scientific principles involving low costs and should use materials available locally.

After months of hard work, the students came up with interesting models. Roopesh Gupta from Kulu Manali has designed a model of cold storage that operates without electricity. It's made of wood and steel sheets raw materials that are easily available. Water and air circulate in the storage through tubes, keeping it cool. There is the modified rain gauge made of wood, plastic bottles, rubber funnels and tubes. The work by Ashish Dande, a student of Chhatrapati Shivaji School in Maharashtra can be used by just anyone to measure rainfall without going in for an expensive rain gauge.

Another model that has attracted a lot of attention is an automatic railwaycrossing by R D Prince and Rohit Mohan from Ernakulam, Kerala. The signals operate through magnetic waves. ``It cannot fail,'' guarantee the makers. Prince and Mohan were inspired to devise the model after the recent railway tragedy in Gaisal.

The participants, along with their unique models, will reach Rajkot on November 27. The exhibition will be held on the Race Course ground. ``As we are expecting a lot of visitors, we are holding it in the open. The exhibition will be on till December 3. School children from the host city will also display their projects along with the selected exhibits,'' said NCERT official Prof J.S Gill.