Grade 7-9

AnyDigging questions? Up The Reach outFuture [email protected] Terrific Earth Timeline

Campers will learn about the timeline of the history of the Earth, then make their own timeline to scale and predict when important events occurred.

Materials ● String (or long piece of paper, or could use chalk and do activity outside) ● Ruler or tape measure ● Paper ● Pencil ● Scissors ● Tape

Key Words & Concepts

Earth is estimated to be 4.6 billion years old (with an error range of about 50 million years). Scientists learned this by examining the age of rocks found on the Earth’s crust, as well as rocks from the moon and meteorites through radioactive dating. Originally, scientists had tried to find out the age of the Earth using measurements of sea levels, temperatures, or salinity of the oceans, but these methods were all proven to be unreliable because they are ever-changing and cycling processes.

Radioactive Dating: also called radiometric dating or radioisotope dating, this technique used to date rocks and other materials by measuring the amounts of radioactive isotopes and using information about the known decay rate of that radioactive isotope.

Geological Time Scale: a system of chronological dating that relates layers of rock or soil to specific sections of time. It is used to describe the timing and relationships of events that occured. It also allows scientists to accurately date when different creatures and organisms were fossilized.

Geological History of Earth: the description of Earth’s history and major events through the use of the geological time scale Terrific Earth Timeline Procedure

Making Your own Earth Timeline: We are going to make a timeline with a string that is to scale of the actual timeline of the Earth. This means that a certain measurement of the string will accurately represent a certain amount of time in the Earth’s history!

1) Measure out a piece of string (or paper or chalk line) that is 4.6 meters long (460 centimeters). This string is going to represent the entire history of the Earth, using this scale: i) 1 metre = 1 billion years

ii) 1 centimetre = 10 million years

iii) 1 millimetre = 1 million years

2) Label the left end of the string “Planet Earth Formed”, and the right end of the string “Today”.

3) Below are several important events that have occurred since the Earth was formed. Cut out a small square of paper for each event, and write the name of the event on the piece of paper. Try to place the events in the correct order on your Earth history timeline, and place them wherever on the timeline you think it happened. i) Oceans formed

ii) First life on Earth

iii) First aquatic animals

iv) First land plants

v) First land animals

vi) First dinosaurs

vii) Extinction of dinosaurs

viii) First humans

4) On the next page is the answer key for these events. You can either just move your pieces of paper around to the correct place, or you could cut out new pieces of paper with the names of the events and place those in the correct spots so you can compare your hypothesis to the correct answers. Terrific Earth Timeline

Event Distance from Start (Left End of String) “Planet Earth Formed” 0 cm (very left end of string) 4.6 billion years ago Oceans formed 0.2 m (20 cm) 4.4 billion years ago First life on Earth 0.75 m (75 cm) 3.85 billion years ago First aquatic animals 3.9 m (390 cm) 700 million years ago First land plants 4.2 m (420 cm) 400 million years ago First land animals 4.25 m (425 cm) 350 million years ago First dinosaurs 4.375 m (437.5 cm) 225 million years ago Extinction of dinosaurs 4.535 m (453.5 cm) 65 million years ago First humans 5.599 m (459.99 cm) 100 thousand years ago “Today” 4.6 m (460 cm) (very right end of string)

Debrief ● Were any of your predictions correct?

● Were there any events that really surprised you when you found out the correct answer for where they were placed on the timeline?

● What’s the first thing you notice about the Earth’s timeline?

● Where did most of the events take place (first half of the timeline or second half)? #SVatHome

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