Lucille's Summertime Pie

9 inch baked pie or graham cracker crust
3/4 cup sugar
2 T corn starch
1 3/4 cups water
3 oz pkg raspberry Jell-o
Little lemon juice
1 cup blueberries
1 cup raspberries
2 cups strawberries

Mix sugar and corn starch in med pan, add water, bring to a boil. After 1 min remove from heat add dry jell-o. Set in cold water. Fix berries. Stir together. Pour into crust, top with cool whip.