It was, says Alex Savage, one of those lessons you remember for the rest of your life. His Year 7 pupils had been listening to a visitor from Malawi talking about his country. "They had so many questions, and at the end they asked: How can we follow this up, is there any way we can make contact with young people in Africa?"
That was six years ago, and the pupils' enthusiasm prompted the first in a series of school links that have helped promote global citizenship throughout their curriculum.
Alex is advanced skills teacher in ICT and modern foreign languages at Notre Dame High School in Norwich, and he has led the way in using ICT to develop partnerships that enrich learning and allow pupils and teachers to share expertise with schools overseas.
He says: "ICT is about using technology to communicate, and global citizenship education gives you real reasons for communicating."
Alex found that few schools in Malawi have computers - only around 30 per cent have electricity - and with the help of the British Council, he established links with three that had secured refurbished machines.
Together, the partners embarked on a project they named Kwathu, which means "home" in the Chichewa language. Alex says: "Our motto was 'My Home, Your Home, Our Home'.
"If students have the opportunity to compare where they live with someone else's environment, then they appreciate the similarities and differences, and realise that the life they lead has a knock-on effect for people elsewhere on our planet."
A citizenship class at Notre Dame sent disposable cameras to their new friends, and the children swapped snapshots and tales of their everyday lives. Alex says: "In Malawi, the children had to go and collect the family's firewood every morning. Our students had been studying deforestation, and suddenly they were able to comprehend the scale of the issue."
The photos were sent by post, and pupils compared notes in emails sent via their teachers. "You cannot do a school link without email," says Alex.
"Letters are simply not instant enough: you lose momentum."
He set up promotional displays in school, and other departments picked up the baton. RE students looked at needs and wants in both countries. Young artists collaborated to draw and carve spectacular Malawian masks. And Notre Dame's A-level economics students were able to field impressively informed case studies of Malawi as a developing nation.
Teachers in both countries teamed up to create a software resource pack on hydroelectric power. A group from Norfolk visited their colleagues in Malawi, and together they toured a power station, capturing video and putting together PowerPoint presentations.
Alex says: "Before they had a computer, teachers in Malawi had no way of showing coloured pictures to a whole class; there was a chalkboard and one textbook for the teacher. Sharing their expertise with other schools, at home or overseas, was a new experience."
The pack was published on Notre Dame's Global Home website. Two other Norfolk schools took part in the five-year project, and although funding has now ceased, all the Kwathu material is still in use and freely available.
With the help of the local authority, Notre Dame and other Norfolk schools have developed links with French schools in the Toulouse region. Pupils team up to work together in video conferences and online forums, and Alex says the initiative is not only improving his students' French - it has completely changed their impressions of France. "They asked what the Toulouse children did at the weekend, and discovered they were all on their PlayStations. You won't find the French phrase for PlayStation in the textbooks, which are full of imaginary children writing formal letters.
Norfolk is one of the least racially diverse areas in the country, and collaborating with young people from other nations can help dispel any stereotyped views the students have."
There is an international network of Notre Dame Catholic schools, and Alex has forged links with several in the US and Japan. He is a fan of online surveys, and pupils designed a questionnaire to compare lifestyles in the UK and US.
He says: "The answers suggested that our students lead a healthier lifestyle, a stereotype that proved correct. We tend to do more recycling, but our pupils ended up thinking that perhaps they should be recycling even more. The survey made them re-examine their own lives and priorities.
"Our links with Japan have just been established, and key stage 3 geography students will use Japan as their case study of a developed country, posing online questions to their counterparts to help with their research."
Notre Dame's diocese is twinned with a diocese in Cambodia, and Alex plans to use an email link to help pupils in the two countries compare life in their parishes. He says: "Cambodia has a very strong sense of community - it is a developed country in that respect."
His advice for schools: "Rather than trying to bolt on global citizenship as an extra to the curriculum, use it to enhance what you already do. When students communicate with a real audience they produce better work."
His planning is done with the help of Oxfam's curriculum outline for global citizenship, which identifies the knowledge, understanding, skills, attitudes and values young people need to be responsible global citizens.
The outline is featured in Education for Global Citizenship, Oxfam's new guide for schools. Richard Baker, a curriculum adviser for Oxfam's development education programme, says: "The guide explains the educational rationale behind education for global citizenship, and includes case studies and classroom activities to demonstrate how things might look in practice. There are also professional development activities to help teachers get a discussion going.
"The benefits of school links are maximised when there is a strong ethos of education for global citizenship in the curriculum, and the linking activities are clearly connected to the curriculum."