Students measure the permeability of different types of soils, compare results and realize the importance of size, voids and density in permeability response.

Students learn and practice how to find the perimeter of a polygonal shape. Using a ruler, they measure model rooms made of construction paper walls. They learn about other tools, such as a robot, that can help them take measurements....

Echolocation is the ability to orient by transmitting sound and receiving echoes from objects in the environment. As a result of a Marco-Polo type activity and subsequent lesson, students learn basic concepts of echolocation. They use...

This essay serves as a guide to prenatal testing for Down Syndrome and describes breakthroughs in ultrasound techniques which allow doctors to detect Down Syndrome without the need for an amniocentesis procedure.

In this activity, students will experience echolocation themselves. They actually try echolocation by wearing blindfolds while another student makes snapping noises in front of, behind, or to the side of them.

Echolocation of little brown bats has been well studied since the invention of bat detectors, electronic devices that can "hear" the ultrasonic calls bats make, which are usually beyond the range of human hearing. Little brown bats...

Wikipedia offers information on the basics of ultrasound, "Sound or vibrations with frequencies too high to be audible by the human ear."

Explore your prior knowledge about bats and investigate bats' use of echolocation to identify and catch prey. Design a game like "Marco Polo" to demonstrate echolocation.

Read about the different types of welding and how they are done.

This resource features a basic definition of infrasonic. It also explains the difference between infrasonic and subsonic.

An explanation of ultrasound scanning: the procedure, its purpose, and its uses in viewing a fetus, heart valves, and so on.