How can I teach classification using meteorites?
Use sorting tasks and dichotomous keys based on observable features such as metal content, chondrules and crystals, then compare pupils' groups with the scientific classification.
Classification is a key scientific skill, and meteorites provide a manageable, real-world example.
Start with observation. Give groups photographs or specimen cards of a dozen meteorites, showing their insides. Include iron meteorites with Widmanstätten patterns, pallasites with olivine crystals, chondrites with visible chondrules and metal flecks, carbonaceous chondrites that are dark and dull, and achondrites such as eucrites with crystals but no chondrules.
Let pupils invent categories. Ask them to sort the meteorites into groups and justify their choices. Many will separate metal from stone and then split the stones by appearance.
Introduce the scientific scheme. Show the three broad families: stony, iron and stony-iron. Then split the stony meteorites into chondrites, which contain chondrules and were never melted, and achondrites, which were melted. Compare with the pupils' groupings.
Build a key. Pupils write a dichotomous key: Is it mostly metal? Does it have green crystals in metal? Can you see small round grains? They test their key on new examples.
Extend. Older pupils can explore how scientists go further, using chemistry and oxygen isotopes to divide chondrites into groups such as H, L, LL and CM, and adding petrologic types. Discuss why scientists need shared names.
This activity links to biology classification and to the idea that categories are human tools that change when new evidence arrives, as new meteorite groups have been added over the years.