Sorting Materials into Groups

Everything around us is made of materials such as wood, glass, metal, plastic, cotton and paper. The same object can be made from different materials, like a tumbler made of glass, steel or plastic, and one material can be used to make many objects, as wood is used for tables, doors and boats. In this chapter you will learn why we sort materials into groups: grouping makes things convenient to find and helps us study their properties together. You will compare materials on the basis of appearance, where metals usually have a shine called lustre, and hardness, since materials like iron are hard while cotton and sponge are soft and easily compressed. You will also test whether substances such as salt, sugar, sand and chalk powder are soluble or insoluble in water, and whether liquids like vinegar, lemon juice and oil mix with water. The chapter explores which objects float or sink in water, and classifies materials as transparent, translucent or opaque depending on how much light passes through them.

Detailed Worksheet: Sorting Materials into Groups Section A - Definitions (10 marks) 1. What is a material? Name three materials used to make a chair. (2 marks) 2. Why do we need to sort materials into groups? Give two reasons. (2 marks) 3. What is lustre? Name two materials that have lustre. (2 marks) 4. Define soluble and insoluble substances with two examples each. (2 marks) 5. Distinguish between hard and soft materials with two examples each. (2 marks) Section B - Calculations and Applications (15 marks) 6. Name the materials from which each object can be made: (i) tumbler (ii) chair (iii) bag. Give two materials for each. (3 marks) 7. Classify into soluble and insoluble in water: sugar, sand, salt, chalk powder, sawdust, glucose, vinegar, mustard oil, kerosene. (3 marks) 8. Predict whether each object will float or sink in water: a dry leaf, an iron nail, a wooden block, a stone, a plastic ball, a coin. How many float? (3 marks) 9. A student stirs 1 spoon of different substances into 6 glasses of water. Salt, sugar and glucose disappear; sand, chalk and sawdust do not. (i) What fraction of the substances are soluble? (ii) Which insoluble substance settles at the bottom? (iii) Which insoluble substance floats? (3 marks) 10. Give the property that makes each material suitable for its use: (i) glass for windows (ii) steel for utensils (iii) cotton for summer clothes. (3 marks) Section C - Diagrams (10 marks) 11. Draw diagrams of three beakers showing (i) sugar dissolved in water (ii) sand settled at the bottom (iii) oil forming a separate layer over water. Label each. (4 marks) 12. Draw a chart grouping these objects by material: spoon, table, notebook, bucket, window pane, shirt. Use the headings metal, wood, paper, plastic, glass and cotton. (3 marks) 13. Draw diagrams to show light passing through transparent, translucent and opaque objects using a torch. (3 marks) Section D - Analysis and Higher-order Thinking (15 marks) 14. Paheli was told that "all objects with lustre are made of metal." (i) Is this always true? (ii) Why do some metal objects look dull? (iii) How can you check whether a dull iron rod has lustre? (iv) Can a plastic object look shiny? What does this tell you about using shine alone to identify metals? (5 marks) 15. A shopkeeper stores rice, sugar, kerosene and biscuits. (i) Why does he keep sugar and rice in separate containers? (ii) Why should kerosene be kept in a sealed metal or plastic can? (iii) Why are biscuits kept in airtight jars? (iv) How does grouping help him find items quickly? (5 marks) 16. Boojho mixed vinegar, lemon juice, mustard oil and coconut oil with water separately. (i) Which liquids mix completely with water? (ii) Which form separate layers? (iii) How can you separate oil from water? (iv) Why is this property useful in daily life? (5 marks) Instructions: Time allowed 2 hours. Attempt all sections. Draw all diagrams neatly in pencil and label every part.