Take a bottle of vinegar, pick out a few raisins, add a box of baking soda and you have everything it takes to explore buoyancy. Have your child put a cup of water in a glass, add a tablespoon of baking soda and mix it into the water. Add a few raisins. At this point, have your child write her observations down in her science journal. After she's convinced that this is the most boring experiment on earth, have her slowly add 1/2 tbsp. of white vinegar to the water. Almost immediately, the raisins will begin to dance. Why? Even though raisins have more density than the liquid, the air bubbles created by the newly-formed carbon dioxide stick to them. When the bubbles loosen their grip, the raisins sink again.
To continue exploring the properties of vinegar and raisins, play a game of Float or Sink. This experiment introduces your child to the concept of viscosity. Gather four glasses. Fill each one with a liquid: water, vinegar, maple syrup and a fourth liquid of your child's choosing. Have him put a raisin in each glass while closely watching each raisin sink. The raisin that sinks to the bottom last is in the glass that contains the most viscous liquid. Have your child expand on the experiment by filling one container with balsamic vinegar and another with white vinegar. He will quickly discover that different vinegars have different viscosities.
Have your child explore the fermentation process -- and the limits of her patience -- by making raisin vinegar. Add 1/2 lb. of raisins to one quart of distilled water. Pour the mixture into a tightly-capped jar. Have your child guess how long it will take the raisins to turn into vinegar, and write this number into her science journal. Every two weeks, have her taste a drop or two of the liquid and record the results. As the raisins ferment, the liquid turns into raisin vinegar. In addition to exploring fermentation, your child is testing a hypothesis and learning that some experiments take a long time to return results.
Collect four liquids and four dried fruits. Include white vinegar and raisins in the offerings. Blindfold your child and have him pinch his nose. Then have him taste a bit of each liquid and fruit. Can your child correctly identify each substance? This experiment will help your child understand how much of an impact his sense of smell has on the taste of foods. If your child can identify the foods while blindfolded, discuss potential reasons for the identification. Did he feel the texture of the food in his mouth? Was the smell so strong that he could smell it through his pinched nose?