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Craggy crevices

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Activity overview

15 mins
Ages 9 – 11

Science topics:


Take a closer look at this familiar object. Will the class be able to work out what it is? You’ll be working your pupils' observation, reasoning and discussion skills.

Run the activity

You will be zooming in and out of the image above – starting very close and stepping back slowly.

1. Start by asking everyone:

  • What do they think the image is and why?
  • What does the image remind them of and why?

2. Every time you zoom out, ask the class:

  • Can they describe the colours, shapes and textures?
  • What do they think the image is now – have they changed their minds?

Background science

The cracked surface and odd shape of rock cakes gave rise to their name. Made from a mixture of self-raising flour, baking powder, butter, eggs and sugar and baked in the oven, these delicious snacks are a good example of chemistry in action. Mixing baking powder in with the wet ingredients causes a chemical reaction, producing bubbles of carbon dioxide.  As the rock cakes bake in the oven, they rise, trapping tiny air pockets of the batter. This creates the cake's light texture. As it cooks, the wet cake batter bakes into the hardened rock cake; another irreversible change.

Scientists studying Mars use many instruments to help them to map the planet’s surface, just like when you pieced together clues to work out that this was an image of a rock cake. The ExoMars Trace Gas Orbiter houses an instrument called Cassis, whose job is to capture the detail of the planet’s surface so that they can work out exactly where different gases may have originated.


The ExoMars mission is looking for signs of life on Mars. We've got lots of activities to support your own Mars exploration. Read more on our blog! 

Take it further

Watch the film Baking Cookies to see the mixture change in the oven right before your eyes! Experiment with more eggy changes with this Brilliantly Bouncy Egg.
Want have a go at making your own rock cakes? Here's a recipe from BBC Food. 


Image Credit: MShev via Shutterstock