Is there life out there?

Before you begin

• Make sure there are no allergies or intolerances to sugar, soil, aspirin or yeast. Have some gloves handy in case anyone would prefer to cover their hands.
• Collect enough cleaned-out jars for each group to have three each. They don’t need lids. If any of your group, helpers or parents/carers can bring any along with them to make up the numbers, even better.
• Label each set of three jars A, B and C, and prepare the experiment:
  • Fill each jar a quarter of the way up with soil.
  • In Jar A, add a small amount of sugar.
  • In Jar B, add instant dried yeast (the contents of a 15ml packet is enough) and sugar to fill a third of the jar.
  • In Jar C, add powdered Alka-Seltzer (one crushed up tablet is enough) and a small amount of sugar.
• Put out the sets of jars somewhere suitable to do the experiment in small groups.

Run the activity

1. Introduce the topic of searching for life on other planets. See if anyone knows anything about the search for alien life forms by the world’s space agencies.
2. Split everyone into small groups and have each group stand by a set of three jars. Give each group a magnifying glass.
3. Everyone should imagine that the jars contain soil samples brought back from other planets. Explain that they’ll be looking for signs of life in the samples. Everyone will need to consider what’s needed for organisms to survive.

4. One person from each group should take a spoon and carefully scoop a small amount of the soil sample from one of the jars. Someone else should hold up the magnifying glass so that everyone can see the sample. Take care not to touch any of the contents. Anyone who touches any of the substances should wash their hands.
5. Give each group some hot water in a jug, making sure it is no hotter than 40°C to avoid killing the yeast.

6. Each group should pour some water into each jar, then watch what happens.

7. Give each group pens and paper. They should think about the following questions and note down any thoughts they have to discuss later:

• • What might life look like on another planet? Could there be other species similar to humans or would we be more likely to find single-cell organisms?
  • How would we react to finding life elsewhere?
  • How would humans survive on another planet such as Mars? What would the challenges be? Examples could be getting supplies of food and safe drinking water and building shelters.

8. Give everyone 10 minutes with the questions. When this time has passed, have everyone check their jars again.

9. See if anyone has any theories about the alien soil samples in the jars. Ask if anyone thinks any of the jars contain life. When this has been discussed, reveal that:

• • Jar B contains yeast, which is a living organism. This means that the reaction of adding water creates a life process.
  • Jar C contains the Alka-seltzer tablets, which cause a chemical reaction with the water, rather than a life-based reaction.
  • Jar A contains sugar, so adding water will create a simple physical change when the sugar dissolves, rather than chemical or life-based reactions.

10. Gather and discuss the questions from earlier with the notes the groups made. Each group should share a thought or opinion on each question. See what everyone believes about life on other planets, and whether anyone has similar or differing opinions.