Lecture # 15

SCIENCE 1 ASSOCIATE DEGREE IN EDUCATION

Precipitation

Idea of Precipitation

• Some questions to start …….

1. What are clouds? 2. When does it rain?

• These can be good questions to start a conversation in which Student can share their prior knowledge. Listen carefully to their explanations. Encourage them to discuss each other’s ideas and to expand their thinking. Their longer statements, not short phrases, can reveal existing misconceptions.

• Student Teachers may hold many preconceptions about the hydrosphere and atmosphere. In particular, they might have a certain idea about water in its gaseous state (vapour) and the processes by which it changes from liquid to gas (evaporation) and gas to liquid (condensation).

• At his point, it is important to begin to discuss some of the common misconceptions, such as the following:

1. The atmosphere is mostly oxygen 2. All clouds are cold, and therefore, their presence makes the air cold 3. Clouds are water vapour 4. Heat causes water to break up into hydrogen and oxygen—that is,

water is destroyed when it evaporates 5. Air pressure increases with an increase in altitude

Idea of Precipitation continues......

• Make sure Students understand that water evaporates from lakes and rivers and that moisture evaporates everywhere (moist ground, plants, humans, etc.).

• Water remains in the air until it precipitates. (If Students are weak on physical science concepts, teaching what happens on the molecular level when water changes state might be too hard to convey at this point.

• States of matter is covered in unit 6, ‘Properties of matter’). However, if many of them show signs of misconceptions, take the time to have them do an experiment. Let them evaporate some water by placing some wet, dark clothes or tissues in the sun or onto a heater.

• Then have them observe that the water contained in the cloth evaporated without being seen and that it is now in the air of the room.

Idea of Precipitation continues......

Seasons • To explain what causes the seasons, most Students will describe a model

that they probably saw in primary school of the Earth rotating around the Sun on an elliptical path.

• The common misconception is that the warmer summer months are caused by the Earth being closer to the Sun during that time. This misconception may stem from their personal experiences with heat sources, such as radiators or ovens, where the closer you get, the warmer it gets.

• They do not understand that the Sun is so far away that this difference in distance on the elliptical path versus the overall distance to Earth is almost negligible. Therefore, the change in seasons is due to the tilted earth axis.

Seasons continue ……..

• If Students struggle with this idea, spend time experimenting with the Sun’s rays on a surface at various angles. Besides changing the angle, also investigate how different land surfaces heat or cool more quickly depending on their properties (different types of land and water).

• At a minimum, they should conclude that the steeper the angle is between the Sun’s rays and the surface, the higher the temperature. (You could expand the activity to show that the colour and material of the surface also make a difference.)

• Then transition back to the model of Earth rotating around the Sun. Show the effect of the tilted Earth axis as it exposes the surface to the Sun’s rays throughout the year and one rotation. To test their understanding, ask them to explain why the southern hemisphere’s coldest months are July and August and its hottest months are December and January.

Suggested activities

• Conclude this week by discussing the uniqueness of the conditions that we find on Earth. Talk with Students about how these conditions enable life as we know it. Begin by building on the topics covered this week, such as Earth’s atmosphere and hydrosphere and the climate that makes Earth inhabitable.

• Have them draw on their prior knowledge from previous lessons and create a list of items that are unique to Earth and are conducive to life. You can inform them that Earth is often described as an ecosystem. Then ask: what makes this ecosystem so special? What could be factors that result in change?

• They should be able to apply what they’ve learned in unit 2 to this greater scale of considering Earth as a whole. At this point, it is more important for them to gain an understanding of systems and how one change can cause another change than present a response that includes many details.

Suggested activities continue ….• In the second week, explore how water contributes to form and shape the

landscapes. After having discussed the water cycle, it is a natural transition to take a closer look at Pakistan’s rivers, deltas, and coastlines, as well as plate tectonics.

• In week 1, Students learned how essential water is for life on Earth. This week, they look at how water shapes the geophysical features and contributes to an ever-changing landscape. Week 1 introduced them primarily to large distances in earth science by looking at the solar system. Week 2 should introduce the scale of time and how the Earth’s surfaces have changed over hundreds or thousands of years.

• Water and erosion (or deposition/sedimentation) are just a couple of concepts that would naturally fit into discussions this week. You could also cover the rock cycle in this context. Rivers transport large amounts of rocks and sediments downstream. Therefore, Students could follow the ‘journey of a rock,’ which is similar to what they did with water in week 1.

Suggested activities continue …..• This week should be dedicated to preparing Students for their

teaching of science in elementary school. It is essential to support them in making the transfer from their own study of science to becoming a teacher of science in the elementary grades.

• Many teaching strategies and pedagogies learned in this course are transferable to teaching at elementary grades. However, the content, activities, and learning objectives must be adjusted to reflect the difference in age and prior knowledge.