☰ Contents · Natural science

The structure of the Earth; natural phenomena

Lessons 57–58 · 2 lessons · Y.V. Malikova, S.V. Kosyanenko. Natural Science Grade 4, Part 1. Novda Edutainment, Tashkent, 2023; S.V. Kosyanenko, Y.V. Malikova, O.E. Tigay. Natural Science Grade 4, Part 2. Novda Edutainment, Tashkent, 2023
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Natural phenomena

Textbook: Part 2, pp. 105–107
GoalKnow events of non-living nature (day and night, the seasons, earthquakes, volcanoes, mudflows, storms), their causes and safety rules.
New words
volcano · vulqonearthquake · zilzilamudflow · selstorm · bo‘ron
Explanation

The Earth spins on its axis about once every 24 hours: the side facing the Sun has day and the far side has night. The Earth goes round the Sun once a year (about 365 days); because its axis is tilted, sunlight falls at different angles through the year and the seasons change. Fast and powerful changes happen in nature. An earthquake is the shaking of the ground caused by the movement of lithosphere plates. A volcano is a place where molten rock from under the ground (magma) bursts out; magma on the surface is called lava. Uzbekistan has no active volcanoes, but it has earthquakes and mudflows. A mudflow is a rush of mud and stones down mountain streams after heavy rain or fast-melting snow. A storm is strong wind that can break trees. Earthquake safety: get under a strong table, protect your head, stay away from windows and shelves, and leave the building calmly when the shaking stops. In a storm stay indoors; if there is a mudflow risk follow adults’ instructions.

Worked examples
In an earthquake: drop, cover, hold on — under a table.
Class activity

Plan with your family where to take cover in an earthquake and which way to leave, and draw it.

Practice
1
Why do earthquakes occur?
2
How do magma and lava differ?
3
Where do you take cover in an earthquake?