EMLEY First School celebrated two historic events, when an extension was opened on the same day as the school's 150th anniversary.
The extension houses an extra classroom, an administrative office, a kitchen, a toilet for disabled people and new toilets for the children. It cost about £280,000, with most of the cash coming from Kirklees Council.
The extension was officially opened by Philip Hoyle, a Christian worker who conducts occasional assemblies at the school.
Mr Hoyle who travels around schools leading the pupils in worship and giving talks. He works for free, but sometimes receives donations.
The pupils chose him to open the extension.
To celebrate the events, past pupils and current pupils' parents were invited to a reception and to reminisce.
An exhibition featuring events during the school's 150 years was also on show.
Mr Merry said: "It was a very successful double celebration."