The Montessori Clock of Eras: A Practical Guide for Elementary Teachers and Homeschoolers

The Montessori Clock of Eras is one of the key impressionistic materials used in elementary Cosmic Education to help children begin to comprehend the enormous scale of Earth's history. By representing approximately 4.5 billion years of Earth's existence on a familiar 12-hour clock face, children can visually see just how long Earth existed before complex life—and eventually humans—appeared. For elementary children, geological time is almost impossible to imagine through dates alone. Four billion years and sixty-five million years are simply very large numbers. The Clock of Eras turns those abstract numbers into something more concrete, helping children compare the relative lengths of the major divisions of Earth's history.

In my experience the Clock of Eras starts bringing together children's knowledge that the dinosaurs lived along time ago alongside big ideas we see on the Timeline of life such as the Cambrian Explosion.

Where does the Clock of Eras fit in the Montessori curriculum?

The lesson belongs within the wider story of Montessori Cosmic Education. It can be presented after the First Great Story and Laws of the Universe or some people teach it alongside the Second Great Story and link it with the Timeline of Life. 

What is the Montessori Clock of Eras?

The Montessori Clock of Eras is both an impressionistic and factual example of time. It helps student see how old the Earth is, approximately 4.5 billion years, as a 12 hour analogue clock. Each hour on the clock represents around 375 million years. The different colours or divisions show the relative lengths of time in Earth's history. One of its key aims for children to appreciate how old the Earth is and indirectly how little time humans have been on Earth. The aim of this visual aid isn't to test whether the child knows the names and can reguritate the time periods but to understand the vastness of History. 

Why is the Clock of Eras important in Montessori Cosmic Education?

Making enormous numbers visible.
A child can hear "4.5 billion years", but that is extraordinarily difficult to comprehend. The clock gives a more understandable look at those numbers.

Appealing to the elementary child's imagination.
At ages 6–12, children are increasingly able to use reasoning and imagination to explore things beyond their immediate experience. The Clock of Eras gives their imagination something concrete to hold onto.

Giving perspective on humanity's place in Earth's story.
One of the most striking impressions, and one of my favourites that I love to see the child's eyes literally open to is how extraordinarily late humans appear and the tiny slither of time we have been on Earth for.

Creating connections across Cosmic Education.
The material naturally links geology, biology, evolution, zoology, botany and human history which is a key element of Montessori Elementary Education.

THE CLOCK OF ERAS PRESENTATION: 

Before the presentation

• The Clock of Eras is often presented after the First Great Lesson and Laws of the Universe. It can be repeated throughout the child's time in Montessori 6-12 adding more sophistication as the child's understanding grows
• previous experience with the First Great Story is helpful;
• Knowledge of analgoue clocks is particularly useful. 
• While the lesson can help teach facts it is also an impressionistic lesson. 

Materials you will need

A circular shaped cardboard marked with the different areas.

-Hadean (Precambrian) 

-Archean  (Precambrian)

-Proterozoic  (Precambrian - when early life happened)

-Paleozoic

-Mesozoic

-Cenozoic

The intervals are an indication of the approximate time that each geological interval has lasted on earth in relationship to other times. 

You may also want a long piece of card with the same colours to show in a linear fashion.

PRESENTATION:

1. Display the circular Clock of Eras chart.
2. Say that this is a clock shape, discuss what students know about how many minutes are on a clock or time generally
3. Each hour represents a very long period of time 375 000 000 years
4. During the Precambrian earth was formed. The Precambrian  is divided into three periods. At the beginning It was a sphere of gas. The gas got cold and condensed and went back down to earth.
5. You may want to present the Cosmic Dance chart, Experiments from the Laws of the Universe 18-20

• Under the cool earth was hot liquid and gas that erupted and made huge clouds of ashes it helped cool the earth by blocking out the sun.
• The rain fell on the very hot earth and it very quickly evaporated. Slow the earth's crust got cooler and cooler and the rain turned into oceans and lakes. 
• The earth then became able to support very simple life this time was called the Proterozoic

6. Paleozoic Era (Blue) This area was when there was a lot of life in the sea. There was bacteria and protista invertebrates and vertebrates in the sea. Towards the end of this time there were reptiles on the land. 
7. Mesozoic (Brown) This area lasted about 185 million years, it was the time of the dinosaurs 
8. Cenozoic Era (Green) This period began about 65 million years. It is knwon as the Age of Mammals. 
9. Have an unlabelled  circular diagram. Give out labels and have students place them in the right place. 
10. Have a long strip of paper put it around the outside of the circular diagram. Mark it at the different divisions. Now lay it flat and then match the labels to the flat diagram. 

What should children understand from the Clock of Eras?

A child's understanding of the Clock of Eras will be different depending on age and how many times they have heard the concept and worked with materials related to it such as research projects. In order of increasing sophistication these are the aims of the lesson/s.