Topic #10: Sound and Light
Activity #1: Sound Waves (November 27, 2017)
The purpose of this four-part activity was to introduce and observe the properties of sound waves and how sound moves through different mediums. The first part, Dancing Salt, involved holding a vibrating tuning fork near a cup covered with plastic wrap and a pile of salt on top. We observed that the vibrations of the sound waves caused the air molecules to oscillate, transferring the sound energy to the salt, which also began to oscillate (which is why it’s called “dancing” salt!). The second part of the activity, Singing Wine Glass, observed how sound waves travel along the bottom of a wine glass and bounce back to a person’s ears when he/she rubs a slightly wet finger around the rim of the glass. The Amazing Fork activity involved tying a string around a fork, wrapping the ends of the string around the index fingers, and putting the fingers into the ears. When the fork hit against the table, we observed that the sound waves travelled through the strings, through the fingers, and into the ears, producing a loud sound. The last part of this activity, Longitudinal and Transverse Waves, was completed using a long slinky. One person held each end of the slinky and took turns oscillating it back in forth in order to illustrate the longitudinal (left/right) movement for sound waves and the transverse (up/down) movement for light waves.
I would introduce the concept of sound to my students by first explaining how sound waves work and how objects can sound different through different mediums. I would have students come up with a list of various sounds they come across in their daily lives. Students could then get into small groups and complete sound activities, such as the Dancing Salt and Amazing Fork tasks.
Because students may have difficulty understanding how similar objects can produce different sounds and how sound waves work to produce sounds, the lesson on sound could be made easier by having students describe different sounds and their properties (loud/soft, high/low, etc.). Another idea for an activity that I came across in my research would be a homemade xylophone using glow sticks and glasses filled with different amounts of water (http://www.playathomemomllc.com/2011/07/glow-sticks-thinking-outside-the-box/). Hitting the glasses would produce different variations of sound and the glow sticks would add fun colors to make it appear more like a xylophone!
Activity #2: Light Box (November 29, 2017)
This activity involved the use of a light box and three mirrors (plane, convex, and concave) in order to observe how light rays reflect from each of the mirrors at different angles. The plane mirror caused the light rays to reflect at an angle less than (an acute angle) the original light ray. The convex mirror caused the reflected light rays to spread out and the concave mirror caused the reflected light rays to focus together. The purpose of this activity was to observe how light waves reflect off of three different types of mirrors.
The lesson on light could be introduced to students by first explaining how light waves work and how light can appear differently after being reflected from different objects. I would perform the light box activity with the whole class using a larger light box set-up and then having the students discuss their observations in smaller groups.
Difficulties with this activity may include differentiating between the different types of mirrors, as well as sketching the reflections of the light. As mentioned before, this activity could be made easier by using a larger set-up for the whole class in order to ensure that all students understand how to complete the activity. Another fun extension would be to use colored lights to observe the reflections!