Digestion is the process by which your body changes the food you eat to forms that your body can use for repair, building, and energy. Digestion starts in your mouth where special digestive juices change starch into sugar. Starch is a large chemical generally stored in plants and sugar is a type of chemical that your body used to produce energy for everything your body does, from movement to all the chemical reactions that occur.
When you chew a cracker, the bits of cracker mixes with saliva. My mom told me to chew each bite 32 times. Not sure it takes that much chewing for every bite of food, but it is important that the food is thoroughly crushed and mixed with saliva.
An easy experiment for a great science fair project is to chew crackers for different amount of time, spit the chewed cracker into containers, and then test the material for the presence of starch.
CAUTION: Since spit, like all body fluids can contain contagious diseases, properly discard your testing materials, such as flushing them in the toilet.
Test for Starch
Tincture of iodine is used to treat wounds. It can be purchased where first aid supplies are sold. Iodine turns starch a dark blue-black color.
Problem: What affect does chewing time have on the amount of starch digested in the mouth?
Independent Variable: chewing time
Dependent Variable: amount of starch digested
Controlled Variables: size of cracker, type of cracker, testing procedure
Hypothesis: If the size and type of cracker remain the same, as the chewing time increases the amount of starch digested increases.
[In other words, the longer you chew the cracker , more of the starch in the cracker is digested.]
7 small crackers are 7 equal-sized cracker pieces
7 transparent plastic cups
1/2 cup of tap water
tincture of iodine
7 craft sticks
1. Place a cracker in your mouth.
2. Chew the cracker for 60 seconds.
3. Spit the chewed cracker into a cup.
4. Add one tablespoon of water, and then add two drops of tincture of iodine.
6. Take a picture of the contents for a record of the color of the results.
7. Repeat steps 1 through 6 five times, each time reduce the chewing time 10 seconds.
1. Place a cracker in the remaining cup.
2. Add 1 tablespoon of water, and then add two drops of iodine.
3. Using the remaining clean craft stick, thoroughly stir the contents of the cup.