Timeline Activity : Teacher Information

Introduction

This activity is designed to help students to ‘reconstruct’ the history of life on earth. Pinning down when specific events occurred is often difficult and so the timeline should be taken as approximate.

Contents

1 x 20 metre measuring tape

47 ‘organism cards’ with pictures and information about each animal or plant

11 ‘era/period cards’

58 rods and bases to support the cards

Suggestions for using this resource

Stretch out the tape to a length of 10 metres. Explain that this distance represents a time period of 500 million years and that the beginning of the tape represents the present day. Then ask the students to calculate the time periods represented by :

1 metre (50 million years)

10 cm (5 million years)

2cm (1 million years)

1cm (0.5 million years or 500,000 million years)

1mm (50,000 years)

Then establish the rule for working out where to place the cards on the timeline. This involves multiplying the number of million years on the card by 2cm.

e.g. 1.8 million years ago would be positioned at 3.6cm on the tape

400 million years ago would be positioned at 800cm (8metres) on the tape

(Note that this scale has been chosen because it should be possible to fit the tape into an average classroom. If a larger space is available, it is easy to increase the scale.

Using the 20 metre tape provided the scale can be doubled (4cm = 1 million years) or if a longer tape is available the scale can be further increased to achieve a greater ‘spread’ of the cards)

Divide the Organism and Period cards randomly amongst the students. Each student should then collect sufficient rods and bases to support their cards.

Students with Period cards should then calculate where to place them on the timeline (by multiplying by 2cm) and then put the cards in position. This will then give the students an overall picture of the different geological time periods.

Students can then take turns to place their Organism cards on the timeline. Each card has a picture of the organism, a short description and an estimation of the time in which it lived.

When all the cards have been placed on the timeline, it should be possible for students to see a gradual increase in complexity of organisms from 500 million years ago up to the present day. It should also be possible to pick out ‘landmarks’ in evolution such as the first dinosaur, the first mammal etc. The timeline will also show the relatively recent appearance of humans. Note too that the huge gaps in the fossil record and the fact that soft-bodied organisms are less likely to become fossilised means that the ‘early’ organisms are probably under-represented.

Before dismantling the timeline, students could be asked to make a record of some of the information it provides. For example, they could make or be given a simplified timeline on which they have to record the type of organisms present every 10 million or 50 million years.

As an extension/homework activity, students could do some internet research into geological timescales to investigate some of the climatic or related events that occurred at different periods and contributed to the selective pressures on the living organisms that existed at that time.

Useful websites include:

www.totallydifferent.co.uk/fossils/Geological-Timeline.html

www.fosilmuseum.net/PaleobiologyVFM.htm

www.newscientist.com/article/dn17453-timeline-the-evolution-of-life.html