1. Combine first 3 ingredients in a large bowl, stirring until sugar dissolves.
2. Place thawed raspberries in a blender; process until smooth. Strain puree through a fine sieve over a bowl. Discard seeds. Stir puree into yogurt mixture.
3. Pour raspberry mixture into the freezer can of an ice-cream freezer; freeze according to manufacturer's instructions. Spoon yogurt mixture into a freezer-safe container; cover and freeze 1 hour or until firm. Scoop into small dessert dishes, and garnish with fresh raspberries, if desired.
Young Chefs can:
Pour yogurt into bowl
Place top on blender, and press blender buttons with adult supervision
Older Chefs can:
Stir yogurt-milk mixture
Strain raspberry puree