MS-PS4-3: Digital and Analog Signals
Also called NGSS MS-PS4-3 · Topic: Waves and Electromagnetic Radiation · Physical Science
The Official Wording
Integrate qualitative scientific and technical information to support the claim that digitized signals are a more reliable way to encode and transmit information than analog signals.
Clarification statement: Emphasis is on a basic understanding that waves can be used for communication purposes. Examples could include using fiber optic cable to transmit light pulses, radio wave pulses in wifi devices, and conversion of stored binary patterns to make sound or text on a computer screen.
Assessment boundary: Assessment does not include binary counting. Assessment does not include the specific mechanism of any given device.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What MS-PS4-3 Means in Plain English
Students gather information from articles, videos and hands-on tests to argue that digital signals carry information more reliably than analog ones. They learn that digital messages are sent as patterns of pulses, like light flashing through fiber optic cable or radio pulses in wifi.
Students do not need binary counting or the inner workings of any particular device. This builds on sending patterns as codes in 4-PS4-3 and leads to HS-PS4-2, where students weigh the benefits and risks of storing and sending information digitally.
MS-PS4-3 I Can Statements
- I can explain the difference between analog and digital signals.
- I can show why copies of digital messages stay accurate.
- I can use evidence from sources to support a claim.
MS-PS4-3 Worked Example
A copying chain a class can run with tracing paper, pencils and one wavy line drawn on a sheet.
Does a message survive repeated copying better as a smooth line or as a list of numbers?
Set It Up: A wavy line drawn across a sheet with a centimeter scale, tracing paper, pencils and six students in a chain.
- Analog chain: each student traces the line from the previous student's copy, not the original.Six traced copies
- Lay the sixth traced copy over the original.Peaks drift and flatten
- Digital chain: read the line's height at every centimeter and write the heights as a list of numbers.20 heights, like 3, 5, 6, 4
- Each student copies the list from the previous student, then the last one plots the points and joins them.Six copied lists, one plotted line
- Compare both final versions with the original.Number copy matches, traced copy wanders
After six copies the traced line had drifted out of shape, while the number list rebuilt the original line almost exactly.
Why it works: Small errors pile up in every analog copy, but a digital message is a set of clear values that can be checked and copied without change.
Common Mistakes with MS-PS4-3
Thinking digital just means electronic
“A vinyl record is digital because it plays music.”
Try this: Digital means the information is stored as separate values, like numbers or on-off pulses. A record's groove is a smooth analog copy of sound.
Thinking digital signals never have errors
“Digital signals can't pick up noise.”
Try this: Noise still hits digital signals, but each pulse only has to read as on or off, so small noise rarely changes the message.
Arguing from opinion
“Digital is better because it is newer.”
Try this: Support the claim with evidence, like the copying test results or a source explaining how pulses survive noise in fiber cables.
Where MS-PS4-3 Fits
Practice MS-PS4-3
Quick Check
- A photocopy of a photocopy gets blurry. Is that like an analog or a digital copy?
- Why does a fiber optic cable send light as on-off pulses instead of a glow that gets brighter and dimmer?
- A song file copied ten times sounds the same as the first. Why?