Bubble TubesGlue a cork into one end of the plastic tubing and let dry completely. Fill the tube with water to within an inch of the uncorked end. Add a few drops of food coloring. Glue the other cork into the open end. Let dry completely. Tip the tube back and forth and watch the bubble travel (toddlers love this). Experiment! Try oil with a few drops of colored water. Use glycerine instead of water and add glitter or small beads to the liquid. Be safe: Always check to see that the corks are securely glued in place. And don't give tubes with small beads that could get swallowed to toddlers. Tie bows around the ends to give as a gift.