BACKGROUND:
Babies grow within the womb of their mothers. The
sperm of the father unites with the egg of the mother to start the creation of
life. The medical profession divides all pregnancies into three trimesters - a
period of three months. This division is useful because various events, signs,
and developments tend to appear in different trimesters. From a length of
three inches and a weight of one ounce, the fetus grows to some 14 inches and
a weight of two and quarter pounds at the end of the second trimester.
Movements of the fetus become noticeable at about 20 weeks or midway through
the second trimester. The mother's weight gain is the most rapid during these
three months, averaging close to a pound a week.
Within the first week, three layers of cells form
which will later be the start of all organs. The outer layer produces the
nervous system, skin, nails, hair, and tooth enamel. The middle layer produces
the bones, muscles, kidneys, and circulatory system. The inner layer produces
the respiratory and digestive system and the glands.
The genetic material directs the number of cells
at a given time in the growing baby. Two cells (the original egg and sperm)
divide into the 6 trillion cells of a newborn baby. In this lab we want the
students to look at the development of the fetus. All children are curious
about what is going on within a woman who is pregnant, it is something obvious,
natural, and all of us have gone through it ourselves. Question from children
are natural and remember that this is not a morality issue, it is a fact of
life. Describing and explaining pregnancy in a factual method, will make these
students confident of what is going on.
PROCEDURE:
- This lab looks at the development of the baby in the
mother's womb. Students need to measure the fetus during selected
periods of growth. On the lab sheet graph, students need to obtain
the following information: number of weeks of growth; the size of the fetus
at that time; the difference between the last growth and the new growth;
the rate of growth (growth/time); and the percent of growth.
- We suggest that you use a calculator and measure in centimeters
because it makes the math much easier. The answers are below.
Please note that the precision of the fetus growth is simplified.
