Harp String Graph

4.A Use mathematical representations of position versus time graphs generated from a tool used to scale up the vibrations of an object to describe wave patterns and support scientific conclusions about how objects move when they make louder or softer sounds..

• Students to explain that the wave patterns on the graphs of louder sounds had higher amplitude (bigger vertical distances) than softer sounds.
• The frequency (horizontal distances) did not change when the same source was making a louder or softer sound.

If students are able to correctly explain the different patterns for louder versus softer sounds but they do not use the terms amplitude or frequency (or don’t use them correctly) to describe them, consider having them complete Harp String Graph Handout with a partner or with teacher guidance in a small group to reteach these terms. Be sure they have added those terms to their science notebooks, consider adding them to a Word Wall display in the classroom, and remind students to refer to either of those word lists as you continue this unit.

If a student has not been able to explain at all how motion graphs of louder versus softer sounds are different, consider having that student “play with” the guitar again. What does a guitar player need to do differently to make a loud sound versus a softer one? Then consider printing out the four graphs of the motion of the stick and speaker, holding them near the guitar strings, and pointing out the connection between a longer/farther “pluck” and the higher amplitude on the louder graphs. The softer sounds require a smaller pull away from the starting point, as seen in the graphs with lower amplitude.

While the individual Progress Tracker is a tool to help students reflect on their own learning in response to the question being investigated, you can use these as a second piece of evidence of students’ evolving understanding. Encourage students to use this space to share new connections they have made but also to note where they are still confused. Then, have students leave their science notebooks in the classroom open to today’s work so you can quickly scan their Progress Trackers and see what key ideas they understand and note any areas of confusion or uncertainty or questions they still have.