Astrophysics Basics: stars and galaxies

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For a grown-up: Claude is for adults (18+). Copy this, paste it into Claude, and use the answer to explain the lesson to your child.

I'm learning "Astrophysics Basics: stars and galaxies" on The Future Market. Lesson 1: "Light is the messenger: spectra, colour and Doppler".

What the lesson teaches:
- A spectrum is a chart or picture of how much light there is at each wavelength (NASA). Spectroscopy is the study of the lines that different atoms and molecules make (NASA glossary).
- Three kinds of spectra (NASA): continuous (a smooth rainbow), emission (bright lines) and absorption (dark lines). Each element makes its own unique set of lines, so hydrogen does not look like helium.
- What lines tell astronomers (NASA): which elements are present, their temperature and density, how fast material moves (from the line width), and whether a star is orbiting a companion (lines shifting back and forth).
- Colour and temperature (ESA): as an object gets hotter, the wavelength where it shines most gets shorter. Hotter stars look bluer, cooler stars look redder (you met the colour table in course 15.2).
- Wien's law: peak wavelength = b / T, where b = 2.898 x 10⁻³ m·K (NIST) and T is the temperature in kelvin.
- Doppler effect (NASA glossary): the change in wavelength of light (or sound) caused by the motion of the source, the observer or both. Redshift is a shift toward longer wavelengths; a shift toward shorter wavelengths is a blueshift.
- Speed of light: 299,792,458 m/s (NIST), about 300,000 km/s.

The exercise I'm working on:
With an adult, look at a street light, an old-style bulb and an LED through a cheap diffraction grating (or the shiny side of a CD). Never point it at the Sun. Draw what you see for each light: smooth rainbow or bright lines? Write which kind of spectrum each one is.

I'm stuck. Please:
1. Explain the main idea in plain, simple words with one everyday example.
2. Walk me through the exercise one small step at a time. Ask me what I've done so far before giving the next step.
3. Don't just give me the final answer. Help me do it myself, and check my work when I share it.

I'm a parent helping my child (about 8 years old) with a lesson called "Light is the messenger: spectra, colour and Doppler" from the course "Astrophysics Basics: stars and galaxies".

Here's what the lesson says:
We can never visit a star, but its light visits us. If you spread starlight into a rainbow, dark or bright lines appear, like a barcode. Each kind of atom has its own barcode, so the light tells us what the star is made of, how hot it is and even how it moves.

The activity:
With an adult, look at a street light, an old-style bulb and an LED through a cheap diffraction grating (or the shiny side of a CD). Never point it at the Sun. Draw what you see for each light: smooth rainbow or bright lines? Write which kind of spectrum each one is.

Please explain this so an 8-year-old understands: short sentences, a fun everyday example, and no hard words.
Then give me 3 simple questions I can ask my child to check they understood, and a way to do the activity together, one tiny step at a time.