All lessons › Lights out for turtles › Lesson 2
Australian primary science · Year 5 · Lesson 2 of 3
Hatchlings and the glow
Inquiry question: Why do turtle hatchlings crawl towards town lights, and what can a community do about it?
Marked no materials needed
Pattern seeking
What students learn
Turtle hatchlings find the sea by heading towards the brightest horizon. Artificial light from towns travels in straight lines to their eyes and can lead them the wrong way. Communities use knowledge of light to decide how to reduce this.
Success criteria
- I can explain how hatchlings use light to find the sea.
- I can describe the pattern between beach lighting and hatchlings reaching the sea.
- I can evaluate which community response would help most, using the data and what I know about light.
Preparation and materials
Before this lesson: Students know light travels in straight lines from sources and that we see light when it enters our eyes (lesson 1).
- One screen or projector to show this lesson’s student view (the turtle source and data) (or print one student view per pair) — 1
- Workbooks or scrap paper, and pencils — 26
Teacher setup
- Open this lesson’s student view (the turtle source and data) on your screen, or print the student view if the internet is unreliable.
- No other preparation is needed.
Safety and adaptations
Follow school science and equipment risk assessment procedures for the materials used.
Review your school policies and curriculum requirements before teaching.
How to investigate
The lesson sequence should leave pupils with evidence to interpret, not only an activity to finish.
- Pairs read the Mon Repos source and the data table in the student view.
- Describe the pattern between lighting and the percentage of hatchlings that reached the sea.
- Draw a beach ray diagram showing why section C’s hatchlings went the wrong way.
- Rank the community responses from most to least helpful, with a reason for each that uses an idea about light.
- Evaluate the data: what else could have been different between the beach sections?
Teacher modelling prompt
Draw a beach: sea on one side, dunes and a town on the other. Think aloud: “At night, the sea side is brighter, so hatchlings head that way. Now I add a bright street light behind the dunes. Its light travels in a straight line over the dune to the hatchling’s eyes. Now the land side might look brighter. A tall row of trees in the way would block that straight path.” Draw the ray lines.
Record and explain evidence
Recording question: Why do turtle hatchlings crawl towards town lights, and what can a community do about it?
| Beach section | Lights visible from the beach | Hatchlings that reached the sea (%) | Our explanation using light |
|---|---|---|---|
| ________________ | ________________ | ________________ | ________________ |
Example recording headings; record actual observations, including inconclusive results.
Discussion prompt
Which response uses science and also thinks about the people who live there?
Provided example or reference data
Example data: hatchling tracks counted the morning after hatching on four sections of one beach (made up for this lesson, similar in pattern to observations by rangers)
| Beach section | Lights visible from the nest at night | Hatchlings whose tracks went to the sea |
|---|---|---|
| A: dunes and tall trees behind the beach | None | 98% |
| B: a few houses with lights shielded and pointing down | A faint glow | 90% |
| C: car park with bright white lights | Several bright lights | 35% |
| D: same as C, but on a night when the car park lights were switched off | None | 95% |
Check the data source in the teacher lesson. Illustrative or fictional data are not measurements collected by your class.
Check understanding
What should pupils know? How do hatchlings normally find the sea at night?
Explain with evidence: Explain, using how light travels, why a row of tall trees behind the beach helps hatchlings.
Apply the idea: Your family is staying in a beach house near a nesting beach. Name two things you could do at night. Stretch (older students): using the data, explain how you know your actions would make a difference.
Teacher answer guidance and saved classroom work are available through the main lesson experience where supported.