Learning about fossils

Evidence of life that existed hundreds of millions of years ago should be enough to excite even the most ambivalent learner. If not, making their own ‘amber’ fossils will surely do the trick...

A good question to start this lesson is “Do rocks tell stories?” To which the answer is ‘yes’, particularly if they contain the fossilised remains of plants or animals. It may well be children put this suggestion forward as – though they will not have encountered fossils in KS1 – it’s highly likely there will be a few amateur palaeontologists in your class. These enthusiasts may already know that most fossils form underwater when the bones of animals become buried deep in layers of sediment, and that those found on land are usually created in dry deserts and caves, or frozen in ice. They may even have heard of more unusual discoveries, such as the ‘dinosaur mummy’ found in sandstone by the Sternberg family – skin still intact.

As well as encountering expertise in this field, you’re just as likely to come across misconceptions. It’s not uncommon for children to think dinosaurs and humans coexisted, whereas in fact the two are separated by 59 million years. This opens up some useful links to history. Although this is a science lesson, you could look at a timeline from the start of the Earth, adding the ages of some different fossils, and the appearance of the Stone Age.

Today you will…

* Learn how fossils are formed

* Use results to draw conclusions and suggest improvements or new questions.

Starter activity

The song I am a palaeontologist by They Might be Giants provides an upbeat introduction to the lesson – though be warned, it is a particularly difficult earworm to shift. And to recreate the air of excitement and discovery experienced by fossil hunters, you could also sink plastic dinosaurs (or, even better, washed chicken bones) into air drying clay or plaster of Paris and allow to dry. Children can then be given a plastic knife so they can chip away and reveal the ‘fossil’.

Main activities

* Pea-historic remains

Get into groups and ask the children what they think a fossil is and collect their ideas together. Explain that fossils can be made in different ways, using peas as models:

* Fresh peas – not fossilised

* Frozen peas – fossils in ice

* Dried peas – mummified fossils

* Tinned peas – fossils intact

* Mushy peas – fossilised, but changed by the process

* Pea pushed into clay – leaves a fossilised imprint

In pairs, let the children try the following activity on the BBC website (tinyurl.com/tpfossils), which will help them understand what conditions are needed for most fossils to form. Now show the class some images of imprint fossils and explain they are going to have a go at creating their own.

In this activity, children will test different substances to find out which makes the best fossil. First create moulds for your fossils by leaving imprints in clay or plasticine, curving up the sides of your chosen modelling material to make a bowl shape. Then make casts of different materials (plaster of Paris, lard, jelly, alginate, wax, mud) in each mould, and compare the results. Which material makes the best ‘fossils’?

Alternatively, children could make ‘fossil’ bread or biscuits by pressing different things into the dough and seeing what remains of the imprint after cooking.

* Stuck in time

Make a display of fossils and non-fossils (these can be images or the real thing). Ask the children to decide which are fossils and which are not. They must explain their conclusions, or why it is difficult to be sure. Emphasise that fossils are made from living things and are old. You could also show the children some fossils and ask them to talk about which living animals they resemble.

Split the class into pairs and explain that some fossils are remains preserved in ice, and that they are going to see what effect freezing might have on a fossil. To simulate this, children will try freezing different plants, pieces of fish or meat to see how they change. As in the wild, these will not be wrapped in anything. Children can draw or photograph them before and after freezing.

Explain that sometimes insects can get trapped in tree resin, which comes out of a tree when the bark is damaged (it isn’t sap). If the resin get buried in sediment it hardens and becomes like orange glass. Show some images of amber fossils if no examples are available. Sue Hendrikson is a self-taught fossil hunter who specialises in amber.

Having examined some examples, children can have a go at making their own amber fossils. Begin by cutting raisins in half and cutting or shaping these to look like insects. Then grease patty tins with oil and line with greaseproof paper. Put the raisin insects into the indented parts of the tin and then place two barley sugar sweets on top of each ‘insect’. Bake for eight minutes at 180oC, leave to cool and then take off the paper. Any paper that remains stuck to the ‘amber’ can be removed with a bit of water. The resulting ‘fossils’ can be wrapped in clingfilm and hung in the window as an attractive display.

Extending the lesson

* Ask children to draw a simple flowchart to show how a fossil could be made.

* Walk around your local area looking at rocks and objects made from rocks to see if there is any evidence of fossils.

* Ask the children to watch pond snails and to draw / annotate a diagram showing how the snails live. Then get them to imagine that a snail becomes a fossil and they discover it in 10 million years’ time. Ask children to draw what they think it would look like and then discuss how many of the things they found out about the snail earlier they could tell from the fossil.

How did it move? What did it eat? And did it live in water or on land?

Useful questions

* Do rocks tell stories?

* Were humans responsible for killing off dinosaurs? Why / why not?

* Are fossils only found in rock?

* Who are the best known modern palaeontologists and what have they discovered?

* Who is Otzi the ice man?

Switched on Science

The activities in this lesson plan are taken from Switched On Science, a Rising Stars resource created for the new science curriculum (risingstars-uk.com). Covering every year group, it’s packed full of hands-on experiments, creative investigations and new approaches to traditional topics. Free access to Tigtag videos, assessment tests and editable medium-term plans are all included.