4th - Investigating Sound Practice

Students are investigating sound using rubber bands stretched over tissue boxes. They write these journal statements:

• Kai: “The thicker rubber band probably vibrates faster than the thin one.”

• Lila: “When I plucked the thin band, I heard a higher pitch than from the thick band.”

• Jonah: “I think the higher sound means the band is trying harder to move.”

• Priya: “The thick band must want to make a lower sound.”

Which student recorded an actual observation instead of an inference or opinion?

• Kai

• Jonah

• Priya

• Lila

Tags

NGSS.MS-PS4-2

A group hangs metal bars of different lengths from a stand and strikes each one with a mallet. The shortest bar makes the highest pitch, and the longest bar makes the lowest pitch. What best explains this difference in pitch?

• The shortest bar is closest to the floor, so sound travels faster.

• The shorter bar vibrates faster than the longer bar, producing a higher pitch.

• The longest bar is heavier, so it pushes sound waves downward.

• The bars change color as they vibrate, which changes the sound.

Tags

NGSS.MS-PS4-1

NGSS.MS-PS4-2

During a sound lab, Mia writes in her journal: “The highest note on the xylophone sounded prettier than the lowest note.” Which feedback would best help Mia improve her scientific record?

• Add more feelings about which notes you liked best.

• Erase this sentence and write only about the instrument.

• Describe how the notes sounded (higher or lower) instead of prettier.

• Write down what you think caused the sound instead of what you heard.

Students cut three cardboard tubes to different lengths and gently tap each one with a pencil. They notice the shortest tube makes the highest pitch, and the longest tube makes the lowest pitch.

Why does the shortest tube produce the highest pitch?

• The shortest tube is lighter, so sound travels more slowly.

• The air in the shorter tube vibrates faster, creating a higher pitch.

• The longest tube pushes more air, so it has a higher pitch.

• The longest tube is closer to the table, so its sound is lower.

Tags

NGSS.MS-PS4-1

Diego places a plastic ruler on the edge of a lab table so part of it hangs off. He flicks the strip and hears a sound. Then he slides it so that more of the strip hangs off the table and flicks it again. What change will Diego most likely hear?

• The pitch will stay exactly the same both times.

• The sound will disappear the second time.

• The pitch will get lower when more of the strip hangs off the table.

• The sound will get louder but keep the same pitch.

Tags

NGSS.MS-PS4-1

A music club builds a set of metal chimes. The table shows each chime’s length and the pitch it makes when struck. They want a chime that plays a pitch between “high” and “medium.” Which chime length would best meet their goal?

• 6 cm

• 8 cm

• 10 cm

• 14 cm

A class uses a sound sensor to compare two guitar strings, String X and String Y. Both are recorded for the same amount of time.

-The graph for String X shows many waves close together.

-The graph for String Y shows fewer waves farther apart.

Some students say String X must have vibrated faster; others think both strings vibrated the same because they were on the same guitar. Based on the graphs, which conclusion is best supported?

• The sensor must be broken because the strings are on the same guitar.

• Slower vibrations always make louder sounds.

• The string with fewer waves must be made of a different material.

• Faster vibrations create a higher pitch because they produce more sound waves in the same amount of time.

Tags

NGSS.MS-PS4-1

Groups investigate pitch using two different instruments:

- Group 1 plucks rubber bands of different lengths.

- Group 2 taps metal bars of different lengths.

Both groups graph their data. In both investigations, shorter lengths produce higher pitches, and longer lengths produce lower pitches. What combined conclusion best explains why two very different instruments show the same pattern?

• Pitch increases when the vibrating part is shorter and vibrates faster, no matter what material is used.

• Rubber bands always make higher pitches than metal bars, so the graphs cannot really match.

• Air slows vibrations, so only the rubber bands show the true pattern.

• The graphs are unreliable because different instruments can never be compared on one set of axes.