Nov 10: Make a sundial

Issue 198

Mar - Apr 2026

Black-Backed Gulls
Meth & HIV in Fiji
Dung beetles
Centro
Rogaining

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Talking points

Gull spotting

• Editorial

For shame

• In the field

When black-backs attack

• In the field

Two years on Mana Island

• Geo News

Before the flood

• Geo News

A delicious crayfish circle of life

Below are some talking points and activities to pass the time, all relating to today’s story.

Talking points

Discuss the ideas presented in the story with your family—at home or over video conferencing. Find ways to involve as many people as possible, especially those who you know are isolated by the lock-down.

• Have you seen a white “cabbage” butterfly before? Have you seen the damage they do to brassicas? (Find out which vegetables are in the brassica family, if you don’t already know!) Can you imagine a larger version of the white “cabbage” butterfly?
• One of the photos shows a cluster of “great white” eggs. Another shows a group of their caterpillars feeding on a leaf together. How do these photos represent the much greater destructive impact of the great white butterfly, compared to its small white relative?
• The writer describes an “inch-long” caterpillar. How many centimetres are in an inch? Find a ruler and see if you can measure it. Which countries measure in inches? What other measurements belong to the imperial measuring system?
• DOC rebranded the “large white” (as it is known in other countries) to the “great white,” in the hope that an association with the great white shark would help the public understand what a threat it poses. Do you feel like that was a smart move? How might it motivate the public?
• After this article was published, the great white was in fact successfully eradicated. The Nelson public played a huge part in this, working with DOC to find caterpillars and butterflies. In one school holiday, DOC offered $10 for each captured butterfly and this was a great success – over 130 were sent in by children! How would it feel to be part of an eradication mission like this? What invasive species could you help to eradicate – such as moth plant?

Activity: Make a sundial

Have a go at making a sundial! Ancient people used these tools as one of the first methods of recording time. One way to introduce this activity is to talk about the sun as an artist, sketching the message of time on the Earth as it spins.

You will need:

• A piece of paper
• Some rocks for weights
• A pencil
• A flat piece of grass

Step One: Lie your paper down on a flat grassy surface. Pierce the middle of it with your pencil. Weight down the edges of the paper so it doesn’t blow away or swivel on its axis.

Step Two: On the hour, note where the shadow is falling and draw a line along this shadow. Write down what the hour is. Make sure you draw along the length of the shadow as you will notice an interesting change in the shadows’ length as the hours draw towards midday, and after midday.

Step Three: Continue marking the shadow’s position and length on the hour, for several hours. What have you learnt? What might have been a limitation of sundials? What other ancient time-measuring devices could you explore? You might like to try making a water-clock or candle-clock.

Send us a picture of your sundial!