The letters will be shared with elderly people living in care homes not just in Biggleswade but nationwide.
Charity YOPEY runs award-winning befriending schemes between schools and care homes.
During the pandemic it has grown from working with a dozen care homes in the East of England to sending young people's letters to 2,000 care homes across the UK.
"Elderly people living in care homes are big fans of the Queen," said YOPEY founder Tony Gearing MBE. "They will love to be included in these imaginary conversations between schoolchildren and the monarch.
"Even people living with dementia may not have forgotten older events from the Queen's 70-year reign such as her coronation. Having the young people's letters read to them will help them to remember."
YOPEY will choose the best letters to be sent to the Queen by the Lord-Lieutenant of Bedfordshire, Helen Nellis, who represents the Queen in the county,
Helen said: “I’m delighted to hear that young people are marking Her Majesty The Queen’s Platinum Jubilee by writing letters to let The Queen know what they did to celebrate her wonderfully long reign.
“They are contributing to our history by sharing their stories and engaging with our older people. Well done to you all!”
Each letter should be on a single side of paper, photographed or scanned, and emailed to [email protected]. Every school that takes part will be awarded a certificate.