Eloise Sainsbury, eight, and her brother Archie, seven, launched a fundraising campaign inviting people to guess the birthday of a teddy called Billy Bear this week.
All proceeds will go towards improvements to the garden at the stroke unit at the Borders General Hospital in Melrose.
They said: “The money raised will to to making the garden beautiful again, like it should be. This will make the patients smile.”
Fellow Lauder Primary School pupils are being invited to donate £1 and guess the giant bear’s birthday, chosen by headteacher Alan Vannan, to be in with a chance of taking home both Billy the bear and chocolates in time for Christmas.
Other schools are being invited to back the campaign, with St Mary’s Primary School in Melrose already involved and offering a Billy Bear of its own.
Senior charge nurse Jamie Thomson has also promised a tour of the stroke unit to the winning children from the schools involved.
Adults can support the campaign too as Royal Bank of Scotland staff across the region have pledged their support, placing a third Billy Bear in its mobile bank and further ones in its Melrose, Galashiels, Jedburgh, Selkirk, Hawick, Duns, Eyemouth and Kelso branches.
They got involved after Archie and Eloise’s mum Amanda Baitup, a senior personal banker for RBS in Bonnyrigg, told colleagues about her children’s efforts.
All funds raised will be allocated to the stroke unit via the NHS Borders charity the Difference.
Any other schools wishing to get involved can contact Amanda on 07809 425241.
£1 entries, including suggested dates, can also be sent to that number by those set up for mobile banking.