Only one in 10 schools and colleges in Wales is committed to teaching pupils about sustainable development and global citizenship (ESDGC) and must do more, says the chief inspector of schools.
Incorporating the issues into the curriculum is high on the Assembly government's agenda, but a report by inspection agency Estyn has found confusion among staff about what to teach and patchy support from local authority advisers.
All schools in Wales are doing some work on sustainable development but it is only ingrained in the ethos of a tenth of them, and most of the work is going on in primary schools, the report said.
"While schools are enthusiastic about promoting sustainable development, they are often less clear about identifying how and where they can develop ESDGC's associated skills and values," it said.
"It is unlikely that the extent and quality of ESDGC will improve until teachers have a clearer understanding of what it constitutes and how they can apply this in practice."
Schools are being urged to work on issues including energy conservation, healthy living, diversity, global poverty, fair trade and human rights. The government wants the work to be integrated into all aspects of the curriculum, but Estyn said schools were finding it difficult to do so.
Estyn said that where the work is taken seriously, pupils' behaviour often improves. Chief inspector Susan Lewis said: "It is vital that leaders and managers see ESDGC as important so that teaching and learning improve."
Gruff Hughes, general secretary of the Welsh-medium teaching union UCAC, said that while it would encourage teachers to promote the work, due consideration must be given to the time and funding needed to do it.
One school committed to the studies is Bedwas high, in Caerphilly, which has just been awarded the top Green Flag award by the eco-schools scheme for the environmentally-friendly.
"Every subject is delivering an aspect of ESDGC," said assistant head Sue Rivers. "In music, pupils express themselves through protest songs and learning about Africa. In history, they are learning about conflict and ways of resolving conflict, so it's not just being taught in personal and social education as a separate subject."
The school runs a gardening club and a healthy-eating salad bar. Pupils also learn about fair trade and there are plans for a bicycle port, and for the school to switch to low-energy light-bulbs.
Estyn said many schools do more work on sustainable development than on global citizenship, but Bedwas has also developed close links with Japan and Mombasa, in Kenya, with regular exchanges taking place.
"It's simple things like finding out that in Kenya the children will treasure a pencil to the last inch and have to walk miles to school, which helps our children to learn about life around the globe," said Mrs Rivers.
"It's such an important subject area and has certainly made pupils more tolerant and broad-minded."
Dominic Miles, co-ordinator at Cyfanfyd, which promotes education for global citizenship in Wales, said: "ESDGC should be an essential part of every child's education. Children need to be aware of the key issues such as globalisation and climate change that already affect people's lives today and will affect their own lives in the future."