Use a spoon to fill the ice pop molds loosely with small chunks of ice cream. Work quickly so that the ice cream doesn’t melt. You want streaks and chunks of ice cream in the pops rather than for everything to blend together. Avoid packing the molds too tightly. The root beer will fill in the space around the ice cream. Carefully pour the root beer into a corner of each mold, filling it to the top. Depending on how tightly you fill the molds with ice cream, you will probably use about 1 cup of the root beer and almost all of the ice cream. Insert sticks. Freeze until firm, at least 6 hours or up to 1 week. To unmold the pops, run hot water over outsides of molds for a few seconds, then gently pull the sticks. For cherry cola float pops, substitute cold fat cherry cola for the root beer. For purple cow pops, substitute cold Concord grape juice. Makes 8 pops.