You don’t really understand something until you have to explain it to somebody else,” says Richard Edwards, head of science at St George Comprehensive School, Bristol. Within earshot, a 13-year-old is explaining to three children from Year 6 at Whitehall Primary the difference in room and body temperatures, and how the vivid yellow, green and purple patches left by a hand pressed on to a liquid crystal sheet indicated the heat system in the body.

We are at the Human Body Workshop in the St George Hands-on Laboratory and boys and girls from St George Year 9 have each been allocated a small primary group to guide around nine “stations” equipped for demonstrating aspects of the body and senses. They will help the children record their findings in work booklets given them on arrival.

The only adult assisting at a station, happy to be helping with enquiries and making a useful informal contact with the school, is Woman Police Constable Monica Harris, schools liaison officer from Avon and Somerset Constabulary. At Station 1 she is taking fingerprints - a handy way of demonstrating that each individual is different - which are recorded in the work booklet, together with the child’s weight and height. Every 10 minutes the groups of children are shepherded on to the next station.

Richard Edwards, who was a regional winner in the 1994 TES Science Teacher of the Year Award, firmly believes that science has to be made interesting and “have a certain vitality about it”. He had ideas about using a hands-on approach in school long before a brief stint as director of the Bristol Exploratory, the first “hands-on” science workshop in the country. Much of the varied and innovative science teaching Mr Edwards has promoted at the school takes place in the Hands-on Laboratory, set up with a joint ICIAssociation for Science Education curriculum development grant in its own large pre-fabricated building on the school site. At St George, an ethnically-mixed inner-city school, pupils of all abilities take double-award science.

The laboratory also makes an important contribution to the St George School aim of being actively involved in the community. Workshops on the human body, electricity and magnetism and sound and light, all guided by Year 9 and 10 pupils, make science accessible, enjoyable and free - not only to primary schools but also to groups of senior citizens. Recently the visit of an Asian women’s group, staffed entirely by Asian girls with a woman teacher in charge was a great success.

Richard Edwards is particularly pleased that already this year workshops have been organised for two groups from special schools , and a valuable link has been made between sixth-formers on a BTec care in the community course, the hosts and guides, and their physically and mentally handicapped guests.

“When it comes to equipping the workshops, I search everywhere for anything that will trigger a response,” says Richard. He had some difficulty in developing Station 3, at which smell is the sense explored, until he discovered a French game involving blindfolded players who sniff a dozen little pots exuding odours ranging from Lavender to Tiger and have to identify as many as they can. “The smelly thing is a bit of legitimate fun,” he says. “Many kids say this is the station they like best, probably because smell is a perception not usually tested.”

At almost every station the activities can be extended according to the children’s age and ability. Station 4 is an introduction to how the body learns to co-ordinate hand and eye for certain routines. It involves mirror drawing using alternate hands, far more difficult than it looks, and trying to guide a metal loop around the zig-zags of the Buzzle Tester without losing concentration and setting off an alarm by touching one of the curves.

At the Body-Map Station a guide is keeping his group firmly on the task of fitting the internal organs back into a model torso at record speed. “OK, it’s easy,” he admits, “but you’ve got to do it again and say what the bits are as you put them in!” He goes on to insist that they draw and label the position of the organs in their workbooks.

The guides, who receive a certificate after the workshop, are all volunteers, and not necessarily the brightest or best-behaved students in their year. “Sometimes you see qualities in them you may not have been aware of before, ” says Richard. “Being a guide gives them a lot of confidence, which is something many children in this inner-city school lack.” For Caroline Goodman, the visiting teacher from Whitehall Primary, this hands-on session is particularly appropriate for her class who have just completed a project on “Ourselves”.

“Is it real?” is the question most children ask when they see the skull at the Skeleton Station. It is real, as are other bones in the collection. Putting hospital X-rays over a light box to find and name the real broken bones was very popular with the children. “They know all about it,” says Richard, “they all watch Casualty on TV.”

The Ear Station has a model with detachable parts and a machine for determining the range of hearing. Guides who are great at adjusting headphones and switches need a little help in interpreting the complicated scale between the lowest and highest frequencies. Eyes feature next, with investigations of three-dimensional images through special glasses and an exercise in naming the parts of the eye.

“Not all the things we’ve tried have been successful,” admits Richard. “In a brochure I found a working model of a heart. It was ideal for the Pumping Station, but we’ve had to put it away because it started squirting everyone!” However, at the ninth and final station, listening to the pumping of your heart with a stethoscope and taking your pulse before and after some vigorous step-jumping exercises obviously satisfies the visitors.

* There is still time for pupils, parents, colleagues and governors to nominate a teacher for the 1995 TES Science Teacher of the Year Awards, which are run in conjunction with the Association for Science Education. There are two categories: primary (sponsored by ABPI) and secondary (sponsored by Pfizer).The closing date is May 31. For forms and further details, send A4 SAE to ASE, College Lane, Hatfield, Hertfordshire AL10 9AA.