Dissolve gelatin in boiling water in bowl. Stir in sliced strawberries, pineapple and juice. Chill until firm. To assemble: Cut chilled gelatin-fruit mixture into small cubes. Distribute half of cubes among eight individual dessert dishes. To each dish add 2 tablespoons yogurt, then one-eighth of remaining cubes and another 2 tablespoons yogurt; garnish with a fresh strawberry.