Topic: Historical views on the Earth’s shape

Target group

1st‑grade student of high school and technical school (basic programme)

Core curriculum

General requirements

II. Skills and application of knowledge in practice.

1. Using plans, physico‑geographic and socio‑economic maps, photographs, aerial and satellite photographs, drawings, graphs, statistical data, source texts, information and communication technologies and geoinformation in order to acquire, process and present geographic information.

Specific requirements

II. Earth in the Universe: Earth as a planet, consequences of Earth's movements, celestial bodies, Solar System, construction of the Universe. Pupil:

1. characterizes the Earth as a planet of the Solar System.

The general aim of education:

Students learn how the views on the Earth’s shape and its role in the universe have been shaped over the centuries.

Criteria of success

• present how views on the Earth’s shape and its role in the universe have changed in history;

• list evidence of the spherical shape of the Earth;

• present the most important information on the Earth’s shape and dimensions;

• show the Pole Star in the sky;

• describe the Earth’s location in the Solar System and the Galaxy.

Key competences

• communication in the mother tongue;

• communication in a foreign language;

• mathematical competences;

• digital competence;

• learning to learn;

• social and civic competences.

Teaching aids

• computers with internet access and Stellarium installed before the lesson (the program requires installation);

• multimedia resources available under “Historical views on the Earth’s shape” in the e‑textbook;

• interactive whiteboard/blackboard, marker/chalk.

Methods / forms of work

• the problem‑solving methods: structured interview, discussion;

• the demonstrating method: presentation;

• programmed learning: via computer, e‑textbook;

• practical learning: exercises on the subject.

• individual work, work in pairs, and collective work.

Lesson plan overview (Process)

Introduction

1. The teacher defines the purpose of the lesson, informing students about its planned course.

2. The teacher then writes the topic of the lesson on a traditional board or an interactive whiteboard. The students write it in their notebooks.

Realization

1. Discussing the evolution of views on the Earth’s shape, with a presentation of resources available in galleries 1 and 2 under “Historical views on the Earth’s shape”.

2. Discussion with the whole class on the evidence of the spherical shape of the Earth and on the reasons why at first, humanity wrongly believed the Earth was flat.

3. Demonstration how the height of the Pole Star on the horizon depends on the latitude of the observation site. The teacher first presents the infographic attached to the lesson, introducing the students to the location of the Pole Star in the sky. Then, with the multimedia material, the teacher explains how to use the Stellarium program to simulate the location of the Pole Star in the sky for different latitudes.

4. Individual work (or work in pairs if needed). The students, in order to check how much they understood the method presented in the multimedia material, perform an interactive exercise that verifies the level of knowledge acquired from the lesson. The teacher checks whether they performed the exercise correctly, and helps the students who have problems with the task.

5. After that, the students will get familiar with the basic functions of Stellarium (e.g. location window, time setting window, constellation lines) while trying to find the Pole Star as well as the Small and Big Dipper. The teacher clears up all the doubts and helps the students to master the basic use of the program.

Summary

1. The final stage is a short summary of the lesson to systematize and solidify the message, clarify any ambiguities and complete the notes.

2. The teacher gives the students homework: observing the Pole Star in the sky according to the instructions under the lesson in the e‑textbook.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Historical views on the Earth’s shape

Earth is one of the right planets circling the Sun – our closest star. In the galaxy, called the Milky Way, where our Solar System is located, a few hundred of billions of other star have been observed. Many of them are encircled by planets. Most probably, that part of the Univers which we are able to observe contains a few hundred of billions of other galaxies.

For years people have bothered with questions related to the world around and above. They kept wondering: what is Earth? what is its shape and size? In the beginning, they found their answers not by scientific research, but using their own senses to observe what more often than not led them to incorrect conclusions. They would claim that the surface of the Earth is flat or almost flat, being unable to perceive the spherical shape of our planet. People were under impression that the Sun is much smaller in size than the Earth. They were not able to evaluate the distance between the Sun and our planet, thus erring in determining its actual size. What our ancestors saw over their heads during day and night was perceived by them to be a section of a sphere, namely half a sphere, seen from the inside, from a flat surface of the Earth.

Not so long ago, people could not imagine that the Earth looks like a sphere. This changed with some specific observations, such as observation of the horizon, Moon eclipses, vessels coming away from a harbour with calm sea, observation of an angle of the North Star over the horizon and, finally, journeys around the world and space travel proved that the Earth is a sphere or at least its shape closely resembles a sphere.

The first one to determine the Earth’s circumference was Eratosthenes who did it in 230 BC. He published the results of his measurements in his work “On the measurement of the Earth” which was subsequently lost but became know through some other writers. It is believed that Eratosthenes determined the Earth’s circumference in the range from 39,690 km (24,662 mi) to 46,620 km (28,968 mi). Until now, the method Eratosthenes applied has been used for accurate measurements of the Earth. He completes measurements during the summer solstice. He compared lengths of shadows cast at noon in Syene (modern Aswan, Egypt) and in Alexandria. Consequently, he observed that sun rays in Syene reached the bottom of a deep well, i.e. their direction was vertical which meant the Sun was directly overhead. At the same time in Alexandria, located on the very same meridian, according to Eratosthenes, sun rays fell at an angle of 7.2 degrees (which makes 1/50 of a full angle). Eratosthenes also knew that the distance between Syene and Alexandria was about 5000 stadia (about 800 km / 497 mi). He concluded that the Earth’s circumference should be 50 times that which was about 40,000 km (24,855 mi). In reality, the Earth’s circumference measures about 40,025 km (24,870 mi), and its average radius is 6,371 km (3,959 mi).