You will need: Empty water bottle, Plastic bag, Scissors, Thread, Water, Food colouring.
Fill the bottle with water and put a drop of food colouring in the water (this is not necessary but makes it easier to see the jellyfish.
Take the plastic bag and fold it flat. Cut a square of the plastic bag (roughy 10 cm edges). Take the center of the piece of t-shirt bag and make a bubble (it will be a bubble once you wrap some of the thread loosely around the area). Don’t make it too tight, you want to be able to add air to the bubble! Tie the thread.
Now, turn your jellyfish over; you should be able to see the hole leading to the centre of the bubble. Next cut the parts of the t-shirt bag, hanging down from the heading tentacles. You need to cut more away than you leave behind - we had 5 tentacles.
Turn the Jelly fish over and find the opening to the head. Blow into the opening to fill it with air. Add enough water so that the head is half filled with air and half filled with water. Twist the head tight. Stuff it and the tentacles into the water bottle and screw on the cap tight. Turn it up and down and watch the jellyfish swim from the bottom to the top.