Resources: Class presentation, a variety of different rocks, bowls of water, weighing scales and a timer.
Core Handout (2): 2 pages with a space for the children to record their hypotheses, results and conclusion.
Stretch Handout (3): An alternative to the second page of the handout above, with an extra question which challenges the children to explain why it is important to know how water weathers rocks.
Enquiry Skill - Setting up tests
Carefully following a method and using equipment accurately to carry out a scientific enquiry. The method may be designed by teachers or children themselves.
Enquiry Approach - Comparative / fair testing
Conducting a test that controls all but one variable to answer a scientific question.
Use the starter slides to recap on the different types of weathering and how weathering can affect rocks.
In the lesson presentation, the children will learn how rocks can be weathered and eroded by water. They will begin to understand why it is important to understand the effects water has on rocks when choosing the most appropriate rocks for outdoor structures.
Rocket Thinking - Teacher Notes: A key question is an open-ended prompt that can facilitate discussion, address misconceptions or give children the opportunity to probe more deeply into a topic. Encourage the children to discuss this hypothetical scenario, using the pictures on the slides as guidance. They might explore how different houses, buildings, roads and beaches would look if they never weathered, and how industries (such as construction) would be different if this were the case.
Career Film: Take a tour around Widemouth Bay and The Etches Collection Museum on the Jurassic Coast to find out about Jonathan Turner's job. Jonathan works as the Head Geologist for Nuclear Waste Management Services.
Expert Film: This is Jonathan Turner. Jonathan works as the Head Geologist at Nuclear Waste Services. Jonathan explains why it is important to understand how rocks are weathered to do his job as he explores sites to build a Geological Disposal Facility.
Building on the children’s previous investigation on the permeability of rocks, they will now carry out a more in depth investigation to discover the effect of water on different types of rocks.
First of all, the children will test to see if their rock absorbs water or whether the water runs off the rock. Then, the children will submerge the rock in the water to find out if the weight of the rock changes. Finally, the children will look to see if the appearance of the rock changes after it has been submerged in the water.
Before each test, the children will need to make a prediction about what they think will happen. They will also need to think about their method and how they will ensure it is a fair test; for instance, the time each rock is submerged should stay the same. Ensure the children observe and weigh each rock before it is submerged so they can draw comparisons.
Challenge Task: Can the children explain why it is so important to understand how water weathers different rocks?
Discuss the children’s results. Which rock would they choose to build a house from?
Water is one of the primary agents of weathering of rocks. Water can cause physical weathering, chemical weathering, or a combination of both.
In physical weathering, the force of running water can break rocks into smaller pieces. This can happen in several ways. For example, when water flows through cracks in rocks and then freezes, it expands and creates pressure, which can cause the rock to break apart. Alternatively, water can wear away at rocks over time through a process called abrasion. As water flows over rocks, it can carry sediment and particles with it that grind away at the surface of the rock.
In chemical weathering, water can cause rocks to break down through chemical reactions. Water can react with minerals in the rock, such as feldspar and mica, and cause them to break down into new minerals that are more stable in the presence of water. This process is known as hydrolysis. Water can also dissolve minerals in the rock, such as calcite in limestone, through a process called dissolution.
In addition, water can contribute to the growth of plants, which can cause weathering through their roots. As plants grow, their roots can penetrate into cracks in rocks, causing the rocks to break apart over time.
The weathering of rocks by water is an important natural process that can shape the landscape over long periods of time. The effects of water weathering can be seen in the erosion of river valleys, the formation of canyons, and the smooth, rounded shapes of rocks on beaches. Understanding the role of water in the weathering of rocks is important for a range of applications, from geological research to the construction of buildings and infrastructure in areas that are prone to water-related weathering.