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Teacher’s notes

• About the Science IS activities

Integrated strands

Science concept

• Craters are landscape features that can be formed by two different types of geological processes – volcanic processes, and impact from space objects.

Nature of Science Theme

Scientists think critically about the results of their investigations…

Where there are differences between actual and predicted results, scientists need to revise their original hypothesis.

DSSA Investigation Focus

Carrying out an investigation includes choosing an appropriate approach…

One approach to an investigation is modelling.

Activity

What you need

• A variety of pictures showing crater-like holes caused by:
  • volcanic activity (for example, Lake Taupo)
  • impact (for example, craters on Mars, the Moon, and on Earth in Siberia, Arizona and Tapanui (NZ)).
• For modelling impact craters:
  • flour or other light-coloured material to represent layers. (If only white sand is available to represent bedrock, use a dark powder for the layers, such as flour mixed with cocoa or paint powder.)
  • a bag of dark-coloured sand (to represent bedrock)
  • newspaper
  • a shallow box
  • a knife or spoon for levelling
  • a sieve
  • two chairs
  • various-sized objects, such as marbles and golf balls (to act as meteorites).
• Optional:
  • Making Better Sense of Planet Earth and Beyond
  • Volcanoes, Building Science Concepts, Book 12.

Note: Supporting activity resources are provided below.

Focus

• Where do we see craters in New Zealand?
• How do we recognise craters in the landscape?
• How do craters get formed?
• Can craters change over time?
• What would you like to know about craters?

Exploration

1. Show students the crater pictures and discuss what the pictures have in common, and ways in which the pictures differ from each other.
2. Ask:
   • How do you think the various craters formed?
   • Do you think it is possible to tell the volcanic craters from the impact craters? If so, how?
3. Then:
   1. Carry out the following activity to model the effect of an impact.
   2. Place newspaper over the working area of the floor.
   3. Put the box in the centre of the working area.
   4. Fill the box with dark-coloured sand (bedrock) to a depth of 4 centimetres. Lightly compact it and smooth with the levelling tool.
   5. Use the sieve to sprinkle a thin layer of the surface material over the bedrock material.
   6. Choose one student to stand on a chair and drop a ‘meteorite’ on to the landscape.
4. Ask:
   • What pattern is made by the flying debris?
   • Can you see layers of bedrock and surface material in the crater walls?
   • Get the students to investigate the effects of the meteorites hitting various multi-layered surfaces at different speeds and angles.
5. Then:
   • Have the students look again at the pictures of craters.
6. Ask:
   • What similarities do you notice between the craters you have made and the ones in the pictures?
   • What new questions do you have about craters?
   • Challenge students to make a list of the features of the two crater types – volcanic and impact.

Extension

• Use your model to find out the effect of many meteorites hitting a similar area. Does the pattern of the flying debris give you an idea of the order of the different impacts? How could this help scientists determine the relative age of impacts on the Moon?
• How can the features of the two crater types be used to decide the order of events that shaped the surface of a planet or the Moon?

Reflection

• How can modelling activities help scientists test their theories?
• Scientists used to think that the Moon’s craters were volcanic. What helped them change their theories?
• What did you learn about craters from the modelling activity? What new questions did you develop?
• How can your list of features help sort the impact craters from the volcanic ones?
• How does the different ways craters form contribute to the differences in their observable features?