Science lesson plan · 9th grade (Year 10 in England) · 45 minutes
Period and frequency (T = 1 / f)
Light, sound and waves
CCSS NGSS.HS-PS4-1England: GCSE Combined Science: Waves (Physics only: period)
Objective and success criteria
Students will: Period and frequency (T = 1 / f).
- I can answer questions on today's skill on my own, without help.
- I can explain each step and say why it works.
- I can check my answer and spot a mistake.
Before and after
Needs first: Wave speed = frequency × wavelength
Leads to: the next skill in this area.
Materials: Slinky or rope, Mirrors and torches, Mini whiteboards, A diagram or short video clip of the idea, Printed student sheet (below).
Warm-up · 5 min
- Quick retrieval from earlier learning (Wave speed = frequency × wavelength). Students answer on mini whiteboards.
- Show answers together and note who needs support in the main task.
- A wave has a frequency of 10 Hz and a wavelength of 3 m. What is its speed, in m/s? → 30 m/sPrompt: v = f × λ
- Sound travels at 340 m/s in air. What is the wavelength of a 680 Hz sound, in metres? → 0.5 mPrompt: Rearrange v = f λ to find λ.
- A wave has a frequency of 2 Hz. What is its period (the time for one wave), in seconds? → 0.5 sPrompt: Period T = 1 ÷ frequency.
Hook · 5 min
- Ask the class to make a wave with a rope or slinky and describe what moves and what doesn't.
- Share the objective: Period and frequency (T = 1 / f). Read the success criteria together.
I do: model it · 10 min
- Work through the example out loud, saying why you do each step, not just what you do.
- Example: A wave has a frequency of 5 Hz. What is its period, in seconds?
- Step 1: 1 ÷ 5 = 0.2
- Step 2: So the answer is: 0.2 s
- Answer: 0.2 s
- Pause after each step and ask a student to say what comes next.
We do: guided practice · 10 min
- Do these together. Students try each step on whiteboards before you reveal it.
- Use the hints as prompts rather than giving the answer.
- A wave has a frequency of 50 Hz. What is its period, in seconds? → 0.02 sPrompt: Period is the time for one complete wave.
- One complete vibration takes 0.5 s. What is the frequency, in Hz? → 2 HzPrompt: f = 1 ÷ T
You do: independent practice · 10 min
- Students work on the student sheet. Circulate and check the first two answers of every student early.
- Students who finish: write a question of their own for a partner, with the answer.
The 8 questions are on the student sheet below, with answers in the key.
Exit ticket · 5 min
- Two questions on their own. Sort answers into got it / nearly / not yet to plan the next lesson.
- One complete vibration takes 0.25 s. What is the frequency, in Hz? → 4 HzPrompt: f = 1 ÷ T
- A wave has a frequency of 20 Hz. What is its period, in seconds? → 0.05 sPrompt: Period is the time for one complete wave.
Watch out for
- Everyday meanings of words getting in the way of the science meaning: define key words explicitly.
- Remembering facts without the reason: ask "why?" and "what is the evidence?"
Support and stretch
Support
- Review first: Wave speed = frequency × wavelength.
- Use concrete materials: slinky or rope.
- Give the first step of each question, or a partly worked example to finish.
- Pair with a confident partner for the guided practice.
Stretch
- Explain a common mistake in writing and how to fix it.
- Write a word problem that uses today's skill, then solve a partner's.
Homework and more practice
Free online practice with hints and printable worksheets for this skill: eurekami.com/science/grade-9.
Free lesson plan from eurekami.com/lesson-plan-builder