Lesson Notes By Weeks and Term v5 - Grade 4

Lesson Video

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Performance objectives

• Identify different processes used to change materials.
• Describe how processing alters a material.
• Explain the difference between raw and processed materials.
• Classify products based on how they were processed.
• Design a simple product from a raw material.

Lesson summary

We interact with processed materials and simple products every single day! From the bread you eat to the chair you sit on, most things around us have undergone some form of processing. Processing changes raw materials into things we can use.

Think about it: Maize (mealies) from a farm doesn't look like the pap you eat for dinner! Processing involves changing raw materials in some way. This week, we'll explore different processing methods and how they create useful products. Understanding this helps us appreciate where things come from and how they are made.

Lesson notes

What is Processing? Processing means changing a raw material into something more useful. A raw material is something found in nature that hasn't been changed yet. Examples include maize, wood, clay, and wool. A processed product is what you get after changing the raw material. Examples include mealie meal, furniture, bricks, and a woolen scarf.

Processing can involve: Changing Shape: Wood can be cut and shaped to make a table. Clay can be molded into a pot.

Mixing: Different ingredients can be combined to make something new, like a cake.

Heating: Cooking food or melting metal are examples of heating.

Grinding: Crushing something into smaller pieces, like grinding maize into mealie meal.

Cooling/Freezing: Used to preserve food or change its state.

Weaving: Interlacing threads to make fabric. Why Do We Process Materials?

We process materials to: Make them easier to use: Raw maize is hard to eat, but mealie meal can be cooked into pap.

Make them last longer: Freezing fruit prevents it from rotting quickly.

Change their appearance: Dyeing wool changes its colour to make a colourful scarf.

Combine them to create new things: Mixing flour, sugar, and eggs, and baking creates a cake.

Examples of Processing in South Africa: Maize to Mealie Meal (Pap): This is a very important process in South Africa. Maize kernels (the raw material) are dried, cleaned, and then ground into a fine powder called mealie meal (the processed product). This grinding process changes the texture of the maize and makes it easier to cook and digest. Think about the difference between trying to chew on a raw maize kernel and eating soft, cooked pap!

Process: Grinding Raw Material: Maize kernels Processed Product: Mealie meal Clay to Bricks: Clay is dug from the ground (the raw material). It is then mixed with water and shaped into bricks. The bricks are then dried in the sun or fired in a kiln (oven) to harden them (the processed product). This process of shaping and heating makes the clay strong and durable, allowing it to be used for building houses.

Process: Mixing, shaping, drying/heating Raw Material: Clay Processed Product: Bricks Sugar Cane to Sugar: Sugar cane is grown on farms (the raw material). The stalks are crushed to extract the juice. The juice is then purified, evaporated, and crystallized to form sugar crystals (the processed product). This process transforms the sweet juice of the sugar cane into the sugar we use in our food and drinks.

Process: Crushing, purifying, evaporating, crystallizing Raw Material: Sugar cane Processed Product: Sugar Wool to a Scarf: Sheep are sheared and their wool is collected (the raw material). The wool is cleaned, spun into yarn, and then woven or knitted into a scarf (the processed product). This process of cleaning, spinning, and weaving transforms the raw wool into a warm and comfortable scarf.

Process: Cleaning, spinning, weaving/knitting Raw Material: Wool Processed Product: Scarf Importance of Understanding Processing: Understanding how materials are processed helps us to: Appreciate the effort and steps involved in making everyday items. Make informed choices about what we buy and use, considering the environmental impact of processing methods. Develop problem-solving skills by thinking about how to transform raw materials into useful products. See the importance of resources in our community and how we can use these resources to create opportunities. Guided Practice (With Solutions)

Question 1: Name a raw material and a processed product made from it. Describe the process involved.

Solution: Raw Material:* Milk Processed Product:* Cheese Process:* Milk is heated and a special ingredient (rennet) is added. This causes the milk to separate into solid curds and liquid whey. The curds are then pressed and aged to make cheese.

Commentary:* This example demonstrates a common process: changing the state of a liquid (milk) to a solid (cheese) using heat and specific ingredients.

Question 2: What raw material is used to make paper? Briefly describe how paper is made.

Solution: Raw Material:* Wood (from trees)

Process:* Trees are cut down, and the wood is broken down into small pieces. These pieces are mixed with water to make a pulp. The pulp is then spread out thinly, pressed, and dried to create paper.

Commentary:* This example showcases how a raw material is broken down and then reformed into a different shape and texture.

Question 3: Identify the type of processing used in the following: a) Making biltong from raw meat. b) Making jam from fruit. c) Making a clay pot.

Solution: a)

Making biltong from raw meat: Drying and curing (often with spices). b)

Making jam from fruit: Heating (cooking) and mixing with sugar. c)

Making a clay pot: Shaping (molding) and hardening (drying/firing).

Commentary:* This question tests the ability to identify the key process(es) involved in transforming a raw material into a product.

Question 4: Sarah wants to make a fruit salad.