1. Spread the flat sheet out on the mattress that already has the fitted sheet on the bottom and center it. Place the top end of the sheet about 1 inch from the edge of the mattress at the head of the bed.
2. Lift the mattress and pull the top sheet snugly under the mattress.
Do this at both sides of the bed so that the top sheet is firmly tucked under the mattress at the foot of the bed.