Unit 3M.2: Investigating Materials

Transcription

1 Unit 3M.2: Investigating Materials Comparing the properties of different materials. Relationship between material uses and their properties Science skills: Predicting Classifying Observing Experimenting By the end of this unit you should be able to: Compare materials according to their common properties and learn about how they are used. Collect, organize observations and data in tabular and pictorial forms. 28

2 3.9.4, Materials Comparing the properties of different materials. Can you pour paper? Can you fold milk? Why not? Different objects have different properties. What can you do to these materials? Discuss. Materials Coin, marble, key, cotton ball, book, peppercorns, piece of candy, uncooked macaroni Process Skills Observing Enquiring Steps: 1- Look at the objects you have been given. 2- Notice whether they look shiny or dull, hard or soft even smell them!! 3- Record your observations, by ticking in the table that follows: 29

3 Object Shiny Dull Hard Soft Rough Smooth Coin Marble Key Pepper corns Cotton Ball Candy Macaroni Book Using our observations skills we can see that different objects have different properties. 30

4 Material strength: The strength of a material refers to how easy it is to; squash, squeeze or stretch it. Squash Squeeze Stretch Activity: Materials Different types of cups of a similar size made from paper, plastic and ceramic. Process Skills Observing Enquiring Experimenting Steps: 31

5 You will need a paper, plastic and ceramic cup or mug. 1- Choose one cup at a time. 2- Try to crush the cup with one hand. 3- Record your observations; draw a picture of the cup before and after. Cup Observation BEFORE Observation AFTER Time to think: Q1- Which cup was the easiest to crush? Why? Q2- Which cup was the strongest? Why? 32

6 Activity: You want to test different materials used in making socks. Materials Different types of socks made from various materials ie. Football socks, thin socks, tights material socks. A range of recording tools ie; measuring tape, masking tape, weights. Process Skills Observing Enquiring Experimenting Steps: Conduct a fair test to measure which pair of socks has the most stretch. 1. Remember in a Fair Test you can; only change one thing, measure one thing and all other things must stay the same 2. Design your experiment to test the socks. Aim, Materials, Method, Predict now TEST! 3. Results: record your observations in the table 33

7 Observation table: SOCK Thick football socks Normal socks Thin ladies socks Length before (cm) Length after (cm) Represent your observation in a bar chart. Showing how much each sock stretched. 34

8 Shock absorption You want to post a fragile gift to your grandparents who live far away. What material will you use to wrap the gift so that it does not break? Activity: Materials Tissue paper, newspaper, bubble wrap, 6 meringues and a sticky tape. Process Skills Observing Enquiring Experimenting Steps: 1- Wrap each meringue with a different material; 2 with tissue paper, 2 with newspaper and the last 2 with bubble wrap. 2- Mark two heights at 1m and 2m to drop your packages from. 3 - Beginning with the 1m height drop each of the wrapped meringue packages (tissue, newspaper and bubble wrap). Open the wrapping and record your observations. 4 Repeat for each package from the 2m, again record your observations in the table that follows. *Remember your safety when working from heights. 35

9 Wrapping Material Tissue Paper Observations Height 1 metre 2 metre Newspaper Bubble Wrap Time to think: Q1- Which wrapping material will you use to send your fragile gift for your grandparents? Why? 36

10 Melting ice This sculpture is made of ice. Ice is a solid. As long as the sculpture stays frozen, it will keep its shape. If the ice warms up, it will melt and become liquid and change its shape. Activity: Materials Clear plastic cups, ice cubes, stop clock Process Skills Observing Enquiring Experimenting 37

11 Steps: 1-Take 2 cups cup A and B, and place 2 ice cubes in each. 2-Put cup A in a cold place and cup B in a warm place. 3-Predict what will happen to the ice in; Cup A Cup B 3-After 4 minutes observe what happened to the ice in both cups and record your observations. 5-Record your observations again after 10 minutes. Observations Cup A - Cold place Cup B - Warm place 4 minutes 10 minutes Time to think: Q1- In which cup did the ice melt faster? Why? 38

12 Q2- What caused the ice to change form? Exploring Plastics Physical changes can be useful. When you fold a sheet of paper, you can make it change shape. An elastic band changes its shape to hold things. However, if a bridge you were driving on changed shape as much as the paper or the plastic bag, there would be trouble!! Plastics are used in many ways that are useful to us. Some of the properties of plastic are: hard and slippery, soft and rubbery, flexible, light weight, non-rusting (corrosive) and easy to shape (malleable). It also comes in many colours and is cheap to make. These factors allow plastics to be used in lots of ways and for many different purposes. 39

13 Activity: Materials Assorted plastic items; ie. food packaging trays, milk containers, chip packets, drinking cups etc 3 hoops Process Skills Observing Enquiring Experimenting Steps: 1- Collect a range of plastic materials. 2- Test each material using a method to squash, squeeze or stretch and record your observations. Breaks easily Creases with stress whitening Crease 40

14 Material Does it snap? Does it crease? Does it get stress whitening? 41

15 Arrange the 3 hoops like picture below. Sort your items into the Venn hoop diagram according to the results of your test. Crease Stress Snap What change was most common for your items? How many items experienced more than 2 changes? 42

16 Key words: Shock absorption Melting Plastic Key ideas: Materials have common properties such as strength, hardness and flexibility. Key Questions Ahmed used ice cubes to find the warmest classroom in the school. He puts one ice cube on 4 different plates then put them in different classrooms. Ahmed and three of his friends measured the time it took for each ice cube to completely melt. Classroom 1 Classroom 2 Classroom 3 Classroom 4 Time 37 min 48 min 34 min 42 min A-Which classroom would you store your chocolate bar in? Why? 43

17 3.9.6 Materials Relationship between properties of materials and their uses. The objects in the pictures below are made of different materials. The properties of each are suitable for different uses. Why? Discuss. Absorbency Absorbency is how much liquid a material can hold. 44

18 Activity Materials Samples of cotton, wool and nylon, bowl, water, measuring beakers, food colouring, ruler and timer. Process Skills Observing Enquiring Experimenting Problem: A drink has spilled on your desk! You need to clean it up quickly but only have limited materials available to choose from. Which material will be the best to use if you want to absorb as much liquid as possible? Steps: 1- Design a fair experiment using the 3 fabrics to test which will absorb the most liquid. 2- Record your findings and then display them in a table or graph. Time to think: Q1-Which material is best to clean up the spill on your desk? Why? 45

19 Insulation: Insulation is a product that blocks the transfer of heat, helping to keep you, your home and offices either cool or warm. Activity: Materials Cotton fabric, woollen fabric, paper, 3 drinks cans, water, 3 thermometers and sticky tape or glue. Process Skills Observing Enquiring Experimenting Steps: 1- Wrap the 3 cans in the different materials; Can 1: Cotton fabric, Can 2: Woollen fabric and Can 3: Paper *You can use sticky tape or glue to secure the materials to the Can 2- Fill all 3 Cans with cold tap water, all the same quantity. 46

20 3- Take the Cans outside and place them in direct sunlight. 4- Record the temperature outside in the sun? Outside temperature: 5-Predict: What material do you think will keep the heat out the best? Why? 6- Place a thermometer in all 3 Cans. 7- Record the temperature of each Can after 5 mins, 10 minutes and 15 minutes. Materials 5 minutes 10 minutes 15 minutes Cotton Wool Paper Time to think: 1-Which material is the best insulator? Why? 2-Was your prediction correct? 3-What other things could affect how much heat gets into the Can? 47

21 Filtration: Filtration is a method of separating a solid from a liquid. Activity: Materials Various materials as filters ie, paper, fabric, stockings, sieves, fishing net etc, 3 clear sample jars/ cups, 1 clear (500ml) drink container with lid, water, soil, small stones and sand. Process Skills Observing Enquiring Experimenting Steps: 1- Mix together a sample of water, sand, stones and soil in a used drinking bottle. Tighten lid on the bottle and shake gently. 48

22 2- Choose 3 different filters to use in your test. 3- Pour the water mixture through the 3 different filters so it is captured by the clear sample jar/cup 3- Record your observations of the filter and sample jar/cup. Type of filter A Filter Contents Sample Jar/ cup (under filter) B C Time to think: Q1- Which filter captured the most material? Why? Q2- Which sample jar/ cup had the clearest water? 49

23 Making ropes: The strength of materials change when twisted together Project: 1- Ask students to research different types of weaves in different materials i.e. grasses, leaves, plastic, string, rope etc. 2- Students to bring one simple weave to experiment on the materials provided. Some material suggestions: polythene bags, cling film, strips of paper, cotton, wool and palm leaves. 3- Choose 1 or 2 materials to weave. 4- Design a simple fair test to compare the strength of each material before and after it has been woven together. 5- Discuss the results. 50

24 What is paper recycling? Paper recycling is the process of recovering waste paper and remaking it into new paper products Project Investigate paper recycling in Qatar. Your information should include: Process of paper recycling. How it benefits the universe. Some uses of recycled paper. Present your findings as a powerpoint presentation, poster or research project. 51

25 Key Words: Absorbency Temperature Filtration Insulation Key Ideas: Materials can be classified according to common properties. Materials are tested for their uses. Key Questions: Q1) Absorbent materials soak up water well. Reem A B C D and Hessa have 4 equal strips of different types of paper. They want to find out which is the most absorbent. They dip the strips in colored water then take them out again. This picture shows the pieces of paper after they are taken out of the water. 1-What material has soaked up the most water? 2-Circle 2 materials that soak up water well. Paper towel Aluminum foil Plastic Bag Cotton Nylon 52