Lesson Notes By Weeks and Term v5 - Grade 4
Processing: materials and simple products – Week 7 focus
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Processing: materials and simple products – Week 7 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Natural Sciences and Technology
Class: Grade 4
Term: 3rd Term
Week: 7
Theme: General lesson support
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This week, we're going to explore the fascinating world of processing! Processing is how we change raw materials – things we find in nature like wood, sand, or even maize – into useful products.
Think about it: a tree in the forest is just a tree. But when we process it, it can become a table, a chair, or even the paper you write on! Understanding processing helps us appreciate where things come from and how much work goes into making the products we use every day. It's also important for understanding how we can use our natural resources wisely and create jobs in South Africa.
What is Processing? Processing means changing something from its natural state (its raw form) into a more useful or valuable form.
Think about clay: it's just mud until someone shapes it and bakes it in an oven to make a pot.
Or maize: it's just kernels on a cob until it's ground into mealie meal to make pap! Processing often involves several steps.
Raw Materials and Processed Products: Raw materials are materials found in nature or grown on farms that have not yet been changed.
Examples in South Africa include: Wood from trees (e.g., pine, blue gum) Clay from the ground Maize (corn) Wheat Grapes Iron ore Sugar cane Wool from sheep Processed products are the things we get after we change the raw materials.
Examples include: Wooden furniture Bricks Mealie meal Bread Juice Steel Sugar Woollen blankets Examples of Processing Steps: Let's look at some specific examples of how raw materials are processed in South Africa: Example 1: Making Bread from Wheat Growing Wheat: Wheat is planted and grown on farms.
Harvesting: The wheat is harvested when it's ripe.
Threshing and Winnowing: The wheat grains are separated from the rest of the plant. (Sometimes these steps are done by machine).
Milling: The wheat grains are ground into flour.
Mixing: The flour is mixed with water, yeast, salt, and sometimes other ingredients like sugar.
Kneading: The dough is kneaded (worked) to develop the gluten, which makes the bread chewy.
Rising: The dough is left to rise in a warm place. The yeast makes bubbles that make the dough bigger.
Baking: The dough is baked in an oven until it's golden brown.
Cooling: The bread is cooled before it's sliced and eaten.
Example 2: Making Bricks from Clay Digging Clay: Clay is dug from the ground.
Mixing: The clay is mixed with water and sometimes sand.
Molding: The clay mixture is put into molds (brick-shaped containers).
Drying: The bricks are left to dry in the sun or a drying oven.
Firing: The dried bricks are baked in a very hot oven called a kiln. This makes them hard and strong.
Cooling: The bricks are cooled down slowly.
Example 3: Making Wooden Furniture from Trees Felling Trees: Trees are cut down in forests or plantations. (This needs to be done sustainably to protect our forests!).
Sawing: The trees are sawn into planks or boards.
Drying: The wood is dried to prevent it from warping (bending) or cracking.
Cutting and Shaping: The planks are cut and shaped into the different parts of the furniture.
Assembling: The parts are joined together using glue, nails, screws, or other methods.
Finishing: The furniture is sanded, stained, or painted to protect the wood and make it look nice. Why is Processing Important?
Processing is essential for many reasons: Food: Without processing, we wouldn't have bread, mealie meal, juice, canned fruits, or many other foods that keep us healthy and strong.
Shelter: Bricks, wood, and other processed materials are used to build houses and other buildings.
Clothing: Cotton, wool, and other raw materials are processed into fabrics that we use to make clothes.
Jobs: Processing creates jobs for people in factories, farms, and other businesses.
Economy: Processing helps South Africa's economy by creating valuable products that can be sold both in South Africa and to other countries. Guided Practice (With Solutions)
Question 1: Name two raw materials used to make clothes and what type of clothing each is typically used for.
Solution: Cotton: Used to make t-shirts, jeans, dresses, and underwear.
Wool: Used to make sweaters, blankets, scarves, and socks.
Commentary: This question checks understanding of raw materials and processed products in a specific context (clothing).
Question 2: List the steps involved in processing maize into mealie meal (pap).
Solution: Harvesting: Maize is harvested from the fields.
Shelling: The kernels are removed from the cobs.
Cleaning: The kernels are cleaned to remove any dirt or debris.
Grinding: The kernels are ground into a fine powder (mealie meal).
Packaging: The mealie meal is packaged for sale.
Commentary: This question tests recall of the processing steps for a common food item in South Africa.
Question 3: Wood is a raw material. Give three examples of processed products made from wood.
Solution: Wooden Furniture (tables, chairs, beds) Paper Wooden toys
Commentary: This question reinforces the relationship between a raw material and its various processed products.
Question 4: What raw material is used to make glass?
Solution: Sand.
Commentary: This question requires students to connect a less obvious raw material (sand) to its processed product (glass). Independent Practice (Questions Only) Name three raw materials found in South Africa and one processed product that comes from each. Imagine you are a farmer growing grapes. Describe the steps you would take to turn your grapes into juice. Explain why processing is important for our community. Give two specific examples.