# Understanding teeth

Once there were two scientists, Dr. Koony and Dr. Haddy. They wanted to find out whether its better to brush your teeth after you eat breakfast or before you eat breakfast in the morning. They did two different experiments to find out. First, they went to Vivek High School and asked all the girls in Class IV to brush their teeth after they ate their breakfasts the next day, and they asked all the boys in Class IV to brush their teeth before they ate their breakfasts. The next day, when the students came to school, Dr. Koony and Dr. Haddy looked at all the Class IV students’ teeth. They found more cavities in the girls than in the boys. So they concluded that it is better to brush before you eat breakfast.

(1) Do you think this was a good way to find the answer to their question? Explain why or why not.

(2) Did Dr. Koony and Dr, Haddy make any mistakes in their first experiment? How could they have designed the experiment better? Explain.

In the second experiment, Dr. Koony and Dr. Haddy first looked at all the Class V students teeth, and repaired all the cavities they found. Then they asked the Class V girls to brush their teeth after breakfast every day for one year, and the boys to brush before breakfast every day for one year. After one year they examined all the Class V students, and found more cavities in the boys than in the girls. This time they concluded that it is better to brush after you eat breakfast.

(3) Do you think the first or second experiment was a better way to find the answer to their question? Explain why or why not.

(4) Did Dr. Koony and Dr, Haddy make any mistakes in the second experiment? How could they have designed the experiment better? Explain.

(5) Based on the results of both experiments, and on your own knowledge and personal experience, what do you think is the correct answer to the question - is it better to brush before or after breakfast?

Types of Teeth

(1) Examine your friend’s teeth, or examine your own teeth in a mirror. How many different kinds of teeth can you see?  Which teeth look similar to each other?

(2) Different kinds of teeth have different names. Use the names given below to label all the teeth in this picture of the teeth of the upper and lower jaws.

(3) Of the four main types of teeth, molars, premolars, canines, and incisors, which ones do you think are best for grinding food like peanuts?

(4) Of the four main types of teeth, molars, premolars, canines, and incisors, which ones do you think are best for breaking off a bite of a raw carrot?

(5) Of the four main types of teeth, molars, premolars, canines, and incisors, which ones do you think are best for eating sugarcane?

(6) Here are the skulls of two animals. One of them is a herbivore and one is a carnivore. Look at the teeth and tell which is which. Base your answer on your analysis of whether the teeth are good for cutting and grinding grass or for killing animals and tearing off strips of flesh from bones.

Is this a herbivore or a carnivore?

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