On an educational school visit? The class are visiting a church, a temple, maybe a synagogue. They are looking at the building, hearing abou beliefs, but definitely not taking part in acts of worship. One child from a Christian family has not been allowed to go 'for religious reasons'. Clearly it is not a matter of christian policy for children not to be allowed on educational visits of this kind, or more children would have remained in school. But what could lie behind anyone making this decision as a Christian? (the child's father is some kind of christian minister).
In a very multicultural, multi faith school it seemed a bit of a snub.