Digimap for Schools uses the Ordnance Survey National Grid as part of our service. The National Grid is a unique reference system made up of 100 kilometre grid squares identified by two letters which spans the whole of Great Britain.
The National Curriculum now specifics that 4 and 6 figure grid references are now to be undertaken in KS1 and KS2.
The Ordnance Survey have a fantastic webpage that gives very clear and simple instructions to help with conveying these concepts. The website is available here:
https://getoutside.ordnancesurvey.co.uk/guides/beginners-guide-to-grid-references
It also has some magnificient YouTube videos which are very short on 4 and 6 figure grid reference.
Always remember this simple tip when learning or teaching Grid References! :