It's not unusual for today's schoolchildren to visit peers in Europe or beyond. But in the era before mass holidays abroad and weekend breaks on the Continent, pupils on school trips felt like pioneers, returning with secrets of another world.
None more so than the pupils of Chatham Junior Technical School on the Holcombe estate, Kent - now Chatham Grammar School for Boys - who embarked on the first Anglo-German exchange in 1929 with a school in Bremen.
As the visits continued through the next decade until 1938 they were exposed to the darkest period in German history. their teachers saw at first hand how the Nazis took control of German schools as well as the rest of German life.
When the exchange was conceived in the late 1920s, hatred towards the Great War enemy was abating. Germany had accepted the Treaty of Versailles and seemed ready to resume her traditional role as one of Europe's peace-loving nations.
In 1926 the principal at Chatham, Isaac Keen, decided to broaden the curriculum by introducing a foreign language. German was chosen because it was felt to be easier than French for non-linguistic pupils. It also made sense for a school preparing boys for the dockyard and apprenticehips in Medway factories, because so many technical journals and works were printed in German. George McWillie, who also taught history and geography, was chosen to introduce the subject.
German proved popular and McWillie wondered about setting up a pupil exchange. In 1928 a German teacher from Bremen, who was staying nearby, happened to visit Holcombe and agreed to put McWillie in touch with a school in Bremen that taught English.
McWillie had envisaged an exchange of letters for a few years, but the English master at the Realschule in Bremen, Dr Ernst Schutte, was more ambitious. According to Schutte's niece the two met in the Rhineland, an area occupied by British troops after World War I until the late 1920s, and Schutte is said to have voiced his keenness for an exchange - no easy matter in the 1920s as it had never been done before - "to prepare the way for friendly relationships between the two bitter enemies of 1914".
The school discovered that the boys could travel from Chatham to Bremen and back for #163;1.0s.6d each (roughly the same as a week's wages for a general labourer). The pupils probably took about 20-30 shillings each for pocket money.
On June 2, 1929, the first German party landed at Dover and travelled by train to Chatham to meet their host families. Three weeks later the 25 masters and boys from Chatham returned with them on the SS Bremen to Ostende, and made the long train journey across Belgium, the Rhineland and Ruhr, and the flat North German plain.
The first exchange was judged a success - it was mentioned on the national six o'clock radio news - and further visits took place annually until 1938, even in the face of rising tension throughout Europe.
From the earliest days in the exchange the students spent a large part of the visit studying at school in the host language. Each school split one of its classes into two, added the exchange boys, and lessons then went on as normal.
In 1934 the Nazis took education out of the control of the country's numerous states and brought in a national curriculum under education minister Bernard Rust, a friend of Hitler, long-standing party member and Obergruppenfuehrer in the SA (the Storm Troopers).
Hitler made little secret of the importance he attached to education as the vehicle for indoctrinating the impressionable minds of the young. By 1937 about 97 per cent of German teachers were members, willing or otherwise, of the National Socialist Teachers' League and young minds were indoctrinated through the curriculum and the instruction of the Nazi youth movements - of which 77 per cent of 10 to 18-year-olds were members by 1938.
The Nazis trebled the amount of time spent on physical education in all schools to 15 per cent of the timetable. For girls the aim was to create healthy young mothers in the hope that they would produce racially superior babies. They studied eugenics daily for 45 minutes, alternating with "health biology". From 1935 compulsory racial education for all students from the age of six included hereditary and blood purity and the dangers posed to Germans by "alien races", including Jews.
History, biology and PE were the main subjects used for indoctrination, but maths and science were also used. One maths textbook, for instance, asked pupils to make calculations relating to night bombers dropping incendiary bombs, how far apart the craters would be and how many fires would be caused.
One of the participants on the 1937 exchange was Bill Killen, the history master, who still lives in Chatham. In his memoirs of the visit, written for the school, he drew a vivid picture of the changes the Nazis introduced in Bremen, where support for the party was weaker than in other areas.
"For the teachers that time in Germany was a chilling revelation of what Nazidom really meant. People were terrified of making any political transgression. When we wished to discuss politics, householders would talk in low tones and turn up the radio in case they were being bugged by neighbours or, taking us outside, they would choose a lonely place such as the local cemetery."
He recalled the Storm Troopers collecting for the poor; the Hitler salutes given by the German boys at the start of their lesson; and the large number of military aircraft models hanging in the art classroom, where one task set by the teacher was for the class to draw a picture of a bombing raid on an enemy town. In another lesson a German teacher pointed out two Jewish boys and drew attention to their "inferior racial characteristics", such as sallow skin, hair and hooked nose.
One incident revealed the indomitable spirit of the Chatham lads. On a visit to the coastal region of Heligoland the boys were observed by German troops with binoculars and they were ordered to keep their Brownie cameras under cover. However, Mr Killen overheard one of the boys muttering numbers to himself. When asked for an explanation, he revealed that he was pacing between the gun emplacements in order to write down the dimensions. No doubt the budding spy fully intended to pass the information on to the secret service.
When I spoke to two old boys who went on the Bremen exchanges in the 1930s, I asked them what they thought about the links with Nazi Germany. They reminded me that no one really used the term "Nazi Germany" before the war, it was simply Germany. Some of the German boys seemed a little nationalistic - in 1938 they were found handing Nazi leaflets out at the Chatham school - but then all foreigners were thought a little funny at the time.
However, with Hitler's occupation of northern Czechoslovakia in March 1939, preparations for war with Germany began in earnest and the exchange was called off. When war broke out, the Chatham school was evacuated to Faversham and then to Wales. Many of the teachers were called up, among them Mr Killen who joined the RAF. Both schools lost old boys in the fighting - 33 from Chatham - and in October 1944 the Realschule was destroyed by Allied bombing.
The attempt by Dr Schutte to heal the wounds of 1914 appeared to have ended in failure. But Chatham revived its German links with a school in Solingen in northern Germany in the early 1950s, and the exchange continues. But the long train and boat journey from Chatham through Dover to Cologne and then train to Solingen has been replaced by a flight from Heathrow to Duesseldorf.
Bruce Smith is head of history at Chatham Grammar