It's another busy day in the classroom. Thirty-five children are demanding attention and the teacher is busy setting up a science experiment. But for Cambridge deputy head Mike Squire help is at hand - courtesy of a project that puts undergraduates into the schoolroom.
Today, and every Thursday, young civil engineering student Katie Clough spends the afternoon at St Philip's school in Cambridge, helping out with Year 6 science lessons.
Her specialist knowledge is highly prized when it comes to dealing with the children's queries, conducting experiments and giving real-life examples of science in use.
Without her help, the class might have to rely on a teacher's demonstration rather than being able to carry out their own experiments.
The link-up between town and gown is part of Cambridge University's STIMULUS project, a peer-assisted learning (PAL) scheme set up in 1987. One of the first such programmes in the United Kingdom, it has been subject to research that highlights its benefits to primary school teachers and pupils.
The person behind the study is Philip Stephenson, primary science co-ordinator at Cambridge's Homerton College. He wanted to gather evidence to back up a gut feeling about the advantages of STIMULUS - Science Technology Informatics and Mathematics Undergraduate Links between University and Schools - in the primary sector.
"As head of Park Street primary school in Cambridge, I had been involved in STIMULUS and was enthusiastic about its benefits," he says. "When I moved to Homerton, I carried on my involvement and decided to carry out a study to find out if the students' specialist know-ledge was being used, or if they were being treated as just another pair of hands."
The study revealed that 75 to 80 per cent of teachers used the undergraduates as a valuable resource, tapping into their knowledge.
One teacher summed up the benefits simply as: "specialist knowledge, specialist knowledge, specialist knowledge", and praised the students' enthusiasm and willingness.
"Teachers can give children more challenging work when someone with specialist knowledge is on hand to answer their questions," says Mr Stephenson. "This is particularly helpful with more able pupils. Looking back on my own teaching experience, I know the needs of the top few are not being fully met.
"And the children are thrilled. They appreciate the students' youth, and are inspired by their expertise."
Now Mr Stephenson is working to spread the word about PAL schemes, and has just co-authored The Science PAL Resource Pack to encourage higher education institutions to set up voluntary schemes for supporting science in primary schools.
It explains the distinctions between placements of PAL assistants and placements of trainee teachers in schools - PAL assistants go into schools to ease the class teacher's job and to enable the pupils to receive more individual attention - and provides information for higher education institutions, schools and student volunteers.
"PAL schemes are extremely simple to arrange. And there is no shortage of volunteers because the university students enjoy helping in schools and they recognise the benefits to themselves in terms of personal development," Mr Stephenson says.
Before the STIMULUS volunteers go into the classroom, they are briefed on what to expect and given a rundown of the national curriculum and advice on communicating with the children - for instance, using questioning techniques that help pupils to express their ideas and to think for themselves.
Mr Stephenson believes PAL schemes boost the image of teaching among university students at a time when recruitment of primary teachers well-qualified in science and technology is of the highest importance.
"We want to recruit post-graduates. If we can get one or two coming out of the STIMULUS scheme it might have implications for a shortage subject area," he says.
Back at St Philip's, Mr Squire is a staunch supporter of PAL schemes. "A student volunteer is far more than just another pair of hands," he says.
"Last term when we were looking at forces in movement and cable car technology, our volunteer took every child in the class through the scientific principles of movement along the wire. They all did a practical experiment with her.
"I can't think of a disadvantage. The student comes regularly so I can plan lessons knowing she will be part of them. And as a female civil engineering student she is a positive role model."
The undergraduate's specialist knowledge allows her to provide technical information and answer questions that might be outside the teacher's knowledge or experience.
Rosemary Hay, head of the 200-pupil Newnham Croft primary school in Cambridge, is another teacher who values the input of student volunteers.
"Their level of expertise and knowledge in their particular subject is high, and can be immensely helpful," she says.
"We have two student volunteers working with the older children - the experience they offer is more relevant to that age group. But even young children can gain a great deal. They can be motivated and excited by science even if they don't understand it."