A Child's Ideas about Heat Concept - Assignment Example

Assessment 2 A Child’s Ideas about Heat Concept: Part A: Science Research Heat is one of the more difficult to understand concepts in elementary school as most students confuse it with temperature. Heat is a form of energy, specifically, the energy movement from two entities that have different temperatures. Since all objects have thermal energy, heat can also be defined as the transference of thermal energy from an object to its surroundings or to other objects. The Key terms associated with this concept are: Conduction: - transfer of heat through direct contact with an object’s molecules Convection: - the transfer of heat through gaseous and liquid elements such as air and water Emissivity: - it is the difference between the amounts of heat that an object reflects versus the amount of heat the object absorbs. Lower emissivity values signify reduced absorption of heat and increased reflection. The emissivity of an object relies heavily on its color with black objects absorbing more heat as compared to lighter objects. Evaporation: is a process where the molecules in a liquid absorb enough energy to become gasses Radiation: a form of heat transfer where heat is radiated in the form of waves through a vacuum or medium without heating up the medium itself. A good example of this is heat transfer from the sun’s rays or a campfire. Thermal conductivity: the rate at which thermal energy moves through an object Thermal equilibrium: a state occurring when all parts of an object or system have equal temperatures Thermal resistance: a heat property showing how much an object resists the transfer of heat Greenhouse gasses: Gasses that prevent the sun’s heat from escaping the earth’s atmosphere leading to a general increase in temperatures. Renewable energy: energy from a naturally occurring source that is inexhaustible. For example, energy derived from the wind, water, and tides. As noted earlier, heat is often confused with temperature but it is critical to note the differences between the two concepts in science. Heat is the transfer of thermal energy from one object to another caused by differences in temperature and is measured in joules (J). Temperature, on the other hand, measures how cold or hot a substance feels and is denoted in 0C. Therefore, while heat involves the transfer of energy, temperature is a measure of the kinetic energy of an object’s particles. Temperature is measured using a thermometer. There are three ways that thermal energy (heat) can be transferred from an object to another or to its surroundings: i. Conduction ii. Convection iii. Radiation Conduction Conduction is the transfer of heat from a hotter part of an object to the colder part without physical movement of its particles. In conduction, the objects are in direct contact with each other. In conduction, heat is transferred from one object to another through the kinetic energy generated by the collision of molecules (Bird, 2003). As thermal energy moves through the object, hotter molecules which have higher kinetic energy collide at a faster rate with the colder molecules which increases the energy of the cold molecules. This transfer of heat continues until the object achieves thermal equilibrium. Different materials can either be classified as insulators or conductors depending on their efficiency in conducting heat. Materials that facilitate easier heat flow through them are known as conductors and include steel, iron, copper, and silver. On the other hand, materials that do not allow heat transfer through them are known as insulators and include wood, ceramic, rubber, and marble. Convection Convection is the transfer of heat from one place to another through a liquid or gas medium. The heat transfer occurs through expansion of the gasses, or liquids. As the object molecules gain more thermal energy, their kinetic energy also increases causing them to move faster (Bird, 2003, p.206). The molecules vibrate with more kinetic energy and at higher frequencies pushing other molecules further apart, they take up more space. The heated gas or liquid then moves upwards while the colder surrounding liquid or gas moves downwards. When the liquid or gas at the top cools down, it flows downwards repeating the process until thermal equilibrium is achieved. Radiation The word radiation originates from a greek word ‘radius’ which means a beam. Radiation is different from both conduction and convection in that it does not require the objects to be in direct contact with each other. In radiation, thermal energy is transferred as electromagnetic waves that move from source to destination objects without heating the space in between (Bird, 2003, p.206). The movement of heat from the sun to the earth is a good example of radiation. For identical objects constructed of the same material, the thinner object will radiate heat at a faster rate as compared to the bulkier object which explains the designs of home radiators. It should be noted that all objects involved in heat transfer emit weak amounts of radiation which may not be easily perceivable at low temperatures. However, at higher temperatures, the radiation is visible as a red glow coupled with the emission of heat to the surrounding environment. Part B Questions: Interview Date: Time: Place (at child’s home, park etc): Child’s age: Child’s year at school: Child’s gender: The following are the initial questions to be used in the interview. These may change over the course of the interview depending on the child’s understanding of various concepts. 1. What is a thermometer? What is it used for? 2. Define temperature. Define heat concept. Is there a difference between the two terms? How do you measure heat? How do you measure temperature? 3. What is meant by convection? Which is colder between a piece of Metal or a book? Why do you think it is colder? 4. Why does a wool carpet feel warmer than the floor in winter? Can you explain what is happening to make the carpet feel warmer? 5. Using a picture of a beaker on a Bunsen burner: The child can be asked to explain the process from when ice is placed over a fire, its melting, boiling, and eventual evaporation. a. Can you reduce the temperature of ice? b. How is heat transferred from the flame to the beaker? c. How is heat transferred from the flame to the air? d. Using a pencil show using arrows examples of conduction, convection and radiation in the figure above e. Predict what will happen when the water starts heating up and then cold water is added 6. In which direction does heat move? Can heat move downwards? Why or why not? 7. What happens when water starts boiling? Can the temperature of water exceed the boiling point? What is contained in the bubbles observed in boiling water? 8. Using a picture of the sun Explain how heat moves from the sun to the earth? Which form of heat transfer is involved? Can you give other examples of where this kind of heat transfer is found? 9. Why does it feel hotter when you are wearing dark clothes as compared to when you wear white clothes? Explain the process that is happening. 10. Why do some objects conduct heat faster than others? What is the name given to materials that conduct heat? Is air a good or bad conductor of heat? Part C Responses: Science concepts or misconceptions the child holds How you know: quote the student, explain misconception & link to relevant academic literature Temperature and heat are similar The distinction between heat and temperature is one that many children find difficult to understand. Driver et al (2005, p.90) points out that the term heat is used in everyday as a noun (heat in an object), and as a verb where an object is heated. Therefore, in everyday life, heat is used to mean the transfer of energy resulting from variations in temperature as well as the kinetic energy in hot object. The teacher in this case should provide an opportunity for the children to define and explore the subtle meanings and differences between heat and temperature. The child has to understand that an object can have very little heat but high temperatures. Temperature can be understood as a measure of how fast the composite molecules of the object are moving. Other objects can also have a lot of heat but at low temperatures. Heat is simply a function of temperature, the conductivity of the molecules, and the density of molecules in an object. Materials have properties such as hot or cold. Children think that cold is a property of materials and only hot materials can emit heat. Like most children, he had the misconception that materials made of metal are cold while those made with wood or plastic are generally considered as warm when both are assessed at room temperature. However, this is the wrong idea since objects exposed to similar ambient conditions have similar temperatures. The feeling of one object being colder than another is caused by the conductivity of the two materials. Metal is a better conductor of heat as compared to wood and therefore conducts heat faster away from the body. Wood, and plastic, on the other hand, are poor conductors of heat and therefore, conduct heat from the body at a slower rate. This explains the feeling of why one feels metal to be colder than wood or plastic. A similar concept is also applicable to holding a snowball where heat moves from the hand into the snowball through conduction and then moves through the snowball by means of convection. Boiling point of water is 1000C and cannot go higher At first, most children do not understand that 1000C is the boiling point for water without impurities. This value can change depending on the impurities present and the ambient air pressure. Additionally, the child did not realize that the boiling point is only a temperature ceiling for the liquid phase of water (Wallace and Hobbs, 2006, p.84). As the water attains gaseous form, it has the potential to achieve higher temperatures Heat always rises The child may have been confused by all the demonstration of heat concepts where heated molecules are said to rise above cooler molecules. The child should understand that warm particles rise within fluids or gases because of differences in density between the two. Once the air or liquid cools, it descends to the lower levels while warmer air gets elevated (Buxton, and Provenzo, 2007). In such a case, the child has to understand that ‘heat’ is a relative term and can be used to refer to sub-zero temperature differentials. However, in conduction, direction is not important while in radiation heat transfer, heat is dispersed in all directions. Therefore, while heat transfer in mediums and gases occurs through convection where heated molecules rise and cold molecules descend, heat transfer in solids in in any direction. In order to understand the fallacy of this statement, the child first needs to understand the effect of temperature on the density of different materials. Atoms and Molecules get larger as they are heated This is a misconception derived from the concept of how the volume of heated air and liquids increases. However, the increase in volume is not explained by an increase in the volume of the individual atoms. Rather, as temperature increases in the object, the increased kinetic energy in the material causes the molecules to vibrate faster thus moving further and further away from each other (Nardo, 2007). This result in the increased volume observed. Heat and Cold are substances Due to the simplified descriptions of the heat transfer process in course materials, the child talks of heat and cold particles as being passed from molecule to molecule which results in the child thinking that heat and cold are substances. The child has to associate heat with the gaining or losing of temperature while cold refers to a lower temperature relative to a baseline. Cold items do not have heat Most people believe that an object at a temperature of 0C has no heat. However, this statement is only true when measuring using the kelvin scale. 0 Kelvins has a temperature of 0 but 0 Celsius translates to 273 Kelvin (Reid, Groves, Price, and Tennant, 2011, p.97). Therefore, an object at 0 Fahrenheit or 0 Celsius has heat while an object at 0 kelvins does not. Part D Planned Learning Activities: Learning Experience Misconceptions Addressed Outline of Learning Experiences      How temperature affects the density of materials Heat always rises. Due to the explanations in course textbooks, children may be confused into thinking that hot items will always rise. Discussion about Heat Discuss what student knows about heat and its effect on object density. Bottle and Balloon activity 1. Pour about 20ml into a glass bottle 2. Using the provided balance, weigh the water, balloon, and bottle 3. Stretch the balloon over the mouth of the bottle 4. Heat the bottle over a Bunsen burner until the water is boiling. i. What can be observed ii. Can the child explain the processes underlying the observations 5. While still boiling, use appropriate protective gear to place the bottle on a scale and record its weight 6. Leave the bottle and water to cool then write any observations seen after cooling 7. Measure the weight of the balloon and record this information in a table This is a simple activity that can be conducted one-on-one. After the student is through, I can pose reflective questions such as: i. Predicting how weight will change with the when the water and bottle are cooled or heated ii. Predicting changes in the balloon due to heat changes iii. Can the student explain what happens to the water during the heating and cooling processes iv. What would have happened if the hot bottle was immediately placed in a freezer? Specific heat, heat exchange, Heat capacity of different materials Heat is a substance that causes materials to expand. Heat is not energy. Requirements: Pack of balloons Small candles preferably votive candles Plastic cup of water Platter Ignite Appropriately sized ring stand Procedure: Take one balloon and place about 30ml of water in one balloon, inflate it and tie it. Take another 2-3 balloons inflate them and tie it Position the platter on the demonstration bench or table Position the ring stand on the platter and set the votive candle on the platform. The positioning should be such that the flame will be approximately 1 inch from the balloon Light the candle and place each balloon on the ring. The first waterless balloons will pop very quickly and the students will judge how long it took for them to pop. Place the water balloon on the ring. It should take significantly longer to pop (About 3-5 minutes) Ask the students if they can explain the observations NB: A possible variation is heating the balloon on the side to observe what happens. The instructor can also slowly lower another water balloon on the votive candle and watch the flame get extinguished Can the students explain the observations? Part E Reflections: For questions where the child was unable to recall the underlying concepts, I had to change questions to lower blooms taxonomy classes. The questions were structured at Blanks Level III and Level IV and the child may have found it difficult to predict outcomes due to pre-existing misconceptions. Therefore, I would simplify the question to where the child could identify differences between the various categories which falls in Blank’s Level II of questioning. Misconceptions can pose problems with effective learning of science. Therefore where misconceptions exist for one child, they might also exist for others. I would plan activities in class that would address each of the misconceptions found in the interview. The activities would be optimally conducted in group in class to make sure all children get hands on experience. These would be followed by discussions among the group which both forms social bonds among the students but also enhances learning. References Buxton, C.A. and Provenzo, E.F., 2007. Teaching science in elementary and middle school: A cognitive and cultural approach. Sage. Driver, R., Rushworth, P., Squires, A. and Wood-Robinson, V. eds., 2005. Making sense of secondary science: Research into children's ideas. Routledge. Nardo, D., 2007. Kinetic Energy: The Energy of Motion. Capstone. Reid, D., Groves, G., Price, C. and Tennant, I., 2011. Science for the New Zealand Curriculum Year 11. Cambridge University Press. Wallace, J.M. and Hobbs, P.V., 2006. Atmospheric science: an introductory survey (Vol. 92). Academic press. Read More