Put some lukewarm water in the bottle.
Add several spoons full of sugar. A funnel can
be helpful here.
Put the cap on the bottle. Shake the bottle to
dissolve the sugar.
Open the bottle and sprinkle some of the yeast onto the surface
of the water.
Put the opening of the balloon over the mouth of the bottle.
Pull the stem part of the balloon down so that it will not come
Wait. As the yeast starts to work, it will release carbon
What will happen to the balloon?