On a trip to the Royal Society for the Protection of Birds's most urban reserve in Rainham Marshes, Essex, a group of Year 5 pupils from Suttons primary school, Hornchurch, have their first vole encounter. Admittedly, the sighting only lasts seconds as the creatures quickly dive for shelter when exposed. It is a bracingly cold day and it is hard not to envy them as they burrow into the grass and out of the rain and sleet.
There are plenty of other firsts for the pupils on the trip too. It is a chance to explore one of the few remaining inner-Thames marshes, to examine river scenery from an ideal bank side vantage point and to engage in a variety of animal investigations - rolling logs and pond dipping in search of minibeasts of all kinds.
"The Rainham Marshes reserve is definitely a project in development," explains the society's education officer Gerry Pittaway. "We are recognised as the flagship environmental project for the Thames Gateway and the aim is that we become part of a conservation park incorporating our land with a nearby site of special scientific interest and an adjacent landfill soon to be restored as a public space."
Considerable work is under way on the RSPB's land, creating a special study centre and a range of large viewing areas - including tree-top platforms - in the reserve's reed beds, marshland and woodland.
"We are uniquely placed compared with other RSPB reserves," he adds. "Most are in isolated areas, but here there are more than 11 million people within 90 minutes of us, so providing as much appropriate access as possible is our priority. We hope to become an extension of local schools'
classrooms - a place for multiple visits each year rather than special outings."
Two RSPB field educators are on hand to ensure Suttons pupils get the most out of their trip. Steve Hall sets a brisk pace needed on such a freezing day. Apart from a baby egret and some ducks, there are not many birds in evidence, though at other times of the year the area attracts numerous resident and migratory species, some in their thousands.
The purpose of the visit is to build on the pupils' river work and there is plenty to observe on this theme. Pupils are shown evidence of a Neolithic forest jutting out of the mud and three successive human attempts to shore up the river's banks. At the water's edge are the remains of the medieval defences that proved effective for more than 500 years.
Steve points out how these have had to be replaced twice in little over a century - a clear sign of rising water levels. On a more positive note is the "orange peel" lichen clinging to rocks across the site. "The extent of its spread is evidence of about 25 years of cleaner air over London," he says.
We beat a retreat indoors to consolidate students' river learning based on the morning's observations. It is clear that the day has deepened their grasp of competing uses affecting a river such as the Thames, and the kinds of problems such usage can pose, particularly pollution.
"Still, the fact that we often see cormorants here suggests there is a lot of life in the river," points out field educator Alan Tanner.
Though fleeting, the sight of the voles is clearly a highlight. "They were biscuit-coloured," says Lawrence in his trip report.
"Having evaluated the day, I thought it was very successful," says teacher Helen Graham. "No matter how virtual a whiteboard can be, nothing is as good as the real thing. Every child in the class wrote a great deal about the trip - even the ones that can struggle with motivation. An important part of education is creating lasting memories."
For full details of the extensive educational programme on offer to students of all ages: www.rainhammarshes.org.uk. For school visits, contact Gerry Pittaway, tel: 01708 520145 or 07980 610309