Label the body parts that you can see. The following images are also three-dimensional sonograms. Answers to Worksheet Ultrasound works similarly to sonar mapping. A sound wave is sent into the womb, where it bounces off of the fetus and comes back. The amount of time that the sound takes to return and the manner in which the sound reflects off of the fetus are used to make the image.
Doctors use ultrasounds because they are much safer than x-rays.
Fetuses are very sensitive, so x-rays are even more dangerous to them. But sound waves are not very dangerous at all, and there are no known side effects of ultrasounds. It is much easier to see the fetus in the three-dimensional sonogram. This is a sonogram of twins. Extensions Look on the internet for information on ultrasounds and for more sonograms, and have the students analyze them.