Changing Matter Changing States – Activity 2 Lesson Focus Outcomes Natural and Processed Materials 2.12 Distinguishes between changes that can not be readily reversed and those that can. Indicators • Identifies changes in materials using the senses. • Distinguishes changes in matter that can and cannot be reversed. • Conducts simple tests to observe and record changes in matter • Records and discusses observations during investigations. Skills Focus • Identifies • Records • Classifies • Follows a procedure • Investigates Background Information Everything we see and touch is matter. Sometimes we can see and feel matter and sometimes we can’t. Matter is all around us and exists as a solid, liquid or a gas. Most matter can change from one state to another when it is heated or cooled. Some matter, like water, can be easily changed from a solid to a liquid, or a liquid to a gas and back again. It may be ice, steam or water vapour, but it is still water. Water is one of the few substances that can change states and not be permanently changed. Other substances may react to heating or cooling but the changes are not reversible (e.g. burning paper to ash, cooking an egg). When water is warmed it evaporates (as a gas into the air). When warm air touches something cold it condenses and becomes a liquid. Before the Lesson Materials Needed Apple, potato, rock, three pieces of steel wool, two small sealable or snap-lock plastic bags, glass of water, measuring cup, plates, tablespoon, string, balloon, electric frying pan with lid, ice cubes. Preparation • The experiment can be prepared four days prior to the lesson to allow changes in materials to occur, or make observations on day of preparation as Day 1 of observations and leave gaps between observation days or extend observation time. • Select an observation table or part of the classroom where samples can be observed safely. The Lesson Stimulus • (Adult-directed activity.) Demonstrate changes of state in water by heating a frying pan. Place in ice cubes and allow students to observe the change to liquid. This activity can be timed. Turn up the heat and watch the water boil. Notice the steam rising into the air. Ensure students are standing away from the table. Demonstrate how the steam is really water droplets by holding a lid carefully over the steam and watch the steam turn to water droplets and return to the pan (condensation). Boil the water until the pan is empty (evaporation). The air is now filled with invisible water vapour produced from icecubes. Revise and discuss the changes that occurred from the ice block to water vapour. Look at the ice cube. Is it a solid or liquid? When water gets very cold it freezes and when it gets warm it melts into a liquid. When water is heated it becomes steam, which will condense back into water. What to Do • Cut up the apple and potato into pieces and leave on a plate. (The whole apple or potato may not be needed, depending on size.) • Blow up a balloon and tie it with a string to something so it can’t float away. Measure its circumference each day. • Put a cup of water into the measuring cup. Measure its volume each day. • Put one piece of steel wool in a plastic bag with three tablespoons of water and seal the bag. (Try to remove any air.) • Put one piece of steel wool in a plastic bag with three tablespoons of water and leave it open. • Put the third piece of steel wool in a dry place where it can’t be touched. • Put the rock and all the above substances in a safe observation area. • Students observe and record the changes each day for five days. • Discuss and describe the changes that have occurred and record the results over the selected observation day. What do you think has happened to the samples to cause changes (e.g. lost air, exposed to air, evaporated)? After the Lesson Answers The potato and apple rotted and changed colour – they are not the same any more. The water evaporated. The dry steel wool had no change. The rock did not change. The wet steel wool in the open bag allowed air in and rusted, because iron turns to rust when exposed to oxygen and moisture. The wet steel wool that wasn’t exposed to the air should have stayed a similar shape. The balloon didn’t change but got smaller and went limp as some air escaped. However it was still a balloon. Additional Activities • Study the water cycle. Discuss how water is recycled and a precious resource to our Earth. • Collect and test other materials to observe changes in matter. (Burning a match, candles, cooking an egg, etc.) Make a list of irreversible changes. Display Ideas • Display objects on a ‘safe’ table. The students can create a large version of the blackline using coloured card. The results can be transferred to the new chart and extra information about the students’ observations can be attached (written and presented by the students). 44 PRIMARY SCIENCE ~ R.I.C. Publications ® ~ www.ricpublications.com.au ISBN 978-1-925660-54-8 ©R.I.C. Publications Low Resolution Images Display Copy
Changing States – Activity 2 Changing Matter Apple DAY 1 DAY 2 DAY 3 DAY 4 DAY 5 8 7 6 5 4 3 2 1 ©R.I.C. Publications Low Resolution Images Display Copy Potato Cup of water Steel Wool (dry) Steel Wool (wet and sealed) Steel Wool (wet and unsealed) Blown-up balloon PRIMARY SCIENCE ~ R.I.C. Publications ® ~ www.ricpublications.com.au 45 ISBN 978-1-925660-54-8 Rock
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