Education in Physics

education in quantum physics and education physics project topics and also education scotland higher physics questions
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Dr.ShaneMatts,United States,Teacher
Published Date:23-07-2017
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ORDINARY LEVEL SECONDARY EDUCATION PHYSICS PRACTICALS USING LOCALLY AVAILABLE MATERIALS TEACHER'S GUIDEPreface As the era of Alternative to Practical comes to an end, it is my hope that science teachers nationally embrace the new paradigm, that science lessons should be student-centred, competence-based, activity-oriented, and connect with student's life experience. Every student in Tanzania should perform practical exercises, not just the few tested on national exams, but the wider range of hands-on activities teachers should employ to build a deep under- standing in their students. Educational research has identi ed two obstacles to the universal imple- mentation of hands-on science education. First, many teachers themselves learned in Alternative to Practical schools and therefore lack essential expe- rience with hands-on science. Every e ort is already under way to overcome this de ciency. A national in-service training program reaches thousands of educators annually, and a Teachers' Guide has already been written to guide teachers on standard execution of dozens of hands-on activities in Physics. The remaining challenge is a fallacy rooted in ignorance and compla- cency: the idea that the materials required for hands-on science teaching are unavailable to most schools. We reject the notion that science education re- quires expensive, imported materials. Everything required to teach modern science is already available in our villages and towns. The challenge is simply to begin. Science belongs to Tanzania as much as any country in the world. The law of gravity respects no national boundaries; we all feel its e ect and can measure its strength. Those who decry the use of locally available materials as \stone age science" misunderstand the meaning of Science - that it applies universally, in any situation, with any material. Dependence on expensive imported materials teaches students that Science is a foreign concept, to be memorized rather than understood, and that Science lacks application to daily life. Science is the birthright of humanity, as much as Language or Mathematics or Music, and the time has come to embrace what we already own. This Companion Guide was written to equip teachers with the knowledge 1and skills to deliver hands-on science lessons in any school, especially those without standard science laboratories. I hope that this Companion Guide will also inspire school inspectors, examiners, curriculum developers and college tutors to increase their emphasis on the importance of hands-on education, and to reject material de ciencies as an excuse for any absence of practical work. In the same spirit, this Companion Guide seeks to expand the range of approaches to learning Physics and it is my hope that the many stakeholders in science education will embrace alternative methods that enable quality delivery of science education for every student. Prof. Hamisi O. Dihenga Permanent Secretary Ministry of Education and Vocational Training April 2011 2Background Motivation for Writing this Companion Guide Quality science education requires students to perform experiments with their own hands. Unfortunately, research on the situation of secondary science education shows that many students do not perform such experiments. This is due to several factors, all of which can be addressed. First, many teachers themselves do not have enough experience with sci- ence experiments, largely due to the absence of practical education when they themselves were students. Teacher training programs and the new Physics Teachers' Guide seek to address this shortcoming. Second, this lack of experience leads to low con dence for trying new experiments. Science can only be learned through experimentation just as students must perform activities to truly understand the material on the syllabus, so too must teachers. The teacher using this book is strongly en- couraged to perform every one of these experiments to deepen his or her fundamental understanding of Physics. Third, most schools lack traditional laboratory facilities. Many educators therefore assume that this means hands-on activities are impossible. To address this misconception, the Ministry of Education and Vocational Training has decided to prepare this Physics Companion Guide. The ob- jective is to ensure that all secondary school Physics teachers can conduct practical work even if they do not have access to a standard Physics lab- oratory. Speci cally, this book demonstrates that many quality hands-on science experiments are possible with very basic materials. The experiments in these pages require materials available in villages or, at worst, in a regional capital. Standard laboratory materials certainly add value to science teach- ing; this book merely makes it clear that they are not required as a condition for provision of quality education. 3Procedures Followed in Developing the Companion Guide This Companion Guide builds on the work of the Physics Teachers' Guide. In preparation for the Teachers' Guide, educators and subject experts identi ed activities for most of the topics on the ordinary level syllabus. To prepare this Companion Guide with Local Materials, a team of secondary school teachers and science experts from TIE devised methods for performing the activities of the Physics Teachers' Guide using low cost and locally available materials. Description of the Companion Guide Practical investigations address speci c syllabus content. Each topic begins with a short summary of relevant syllabus material. Each activity is intro- duced in that context as a method for students to experiment with the topic of the day. Each activity then states clearly its objectives. Generally, these objectives match the objectives in the Physics Teachers' Guide. The teacher should use both resources, side by side, when preparing activities. Each activity description then lists the required materials. Instructions for the local manfacture of several items are given in the rst section of this book in the section called \Manufacture of Apparatus." If an activity requires the use of materials from this section they will be marked with a star () in the materials list. For example, the materials list may look like this: \Materials: beakers, test tubes, plastic spoon" If you see this, you can refer to the materials list to see a suggested method for making your own beakers. After listing the objectives and materials, the description lists any hazards associated with the activity and precautions teachers should take to minimize these hazards. Next are procedures, both for preparing the activity and for executing the experiment. While preparation steps are generally to be performed by the teacher, the activity steps are often to be performed by the students themselves. The description next outlines the expected results and what conclusions may be drawn from them. Then follow the instructions for cleaning up. The section closes with questions useful for guiding classroom discussion. Students should discuss these questions in groups and share their answers with the class. Many of the activities also include a \Notes" section to provide the teacher with additional information about the activity. This information may be practical or theoretical. 4Application of the Companion Guide This guide is written for teachers to acquire the knowledge and skills needed to lead students in hands-on science learning. While all of the experiments in this companion guide may be performed as demonstrations, the intention is for many of the activities to be performed by the students themselves, individually or in small groups, under the direction of the teacher. To prepare for such lessons, the teacher should attempt these experiments rst. Especially for teachers who are new to hands-on science experimenta- tion, these experiments should, in themselves, provide a useful training. If there are multiple subject teachers at the school, they are encouraged to ex- periment together. Once the teacher has achieved comfort and pro ciency with the given activity, the teacher should integrate the activity into relevant lesson plans. The vision is not for students to be spectators of science, but players themselves. Finally, the teacher is advised to not regard the activities in this book as the only possible activities nor even the only possible activities for these particular objectives. Every educator has ideas for e ective teaching and new ideas are the substance of development. After trying an activity, the teacher is strongly encouraged to devise and attempt alternatives. When possible, teachers should collaborate with each other on such experiments, and share with each other the ideas they develop. The vision is not for teachers to be passive implementors, but innovators themselves. 5Contents 1 Laboratory Equipment 10 Checking Voltmeters and Ammeters/Galvanometers . . . . . . . . . 12 Voltmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Ammeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Usable Ammeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2 Physics Activities for Form I 15 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Construction of a Metre Rule . . . . . . . . . . . . . . . . . . 15 Construction of a Measuring Cylinder . . . . . . . . . . . . . . 16 Construction of Beam Balance . . . . . . . . . . . . . . . . . . 17 Measurement Errors . . . . . . . . . . . . . . . . . . . . . . . 19 Density and Relative Density . . . . . . . . . . . . . . . . . . . . . 20 Relative Density of a Liquid . . . . . . . . . . . . . . . . . . . 20 Construction and Use of a Hydrometer . . . . . . . . . . . . . 22 Applications of Material Densities . . . . . . . . . . . . . . . . 25 Archimedes' Principle . . . . . . . . . . . . . . . . . . . . . . . . . 27 Construction of Eureka Can . . . . . . . . . . . . . . . . . . . 27 Flotation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Conditions of Flotation . . . . . . . . . . . . . . . . . . . . . . 28 Properties of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Surface Tension in Bubbles . . . . . . . . . . . . . . . . . . . . 29 Changing Surface Tension . . . . . . . . . . . . . . . . . . . . 31 Cohesion in a Moving Liquid . . . . . . . . . . . . . . . . . . . 34 Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 Determining Adhesion and Cohesion . . . . . . . . . . . . . . 36 Capillarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Conservation of Energy . . . . . . . . . . . . . . . . . . . . . . . . . 40 Potential Energy of a Spring . . . . . . . . . . . . . . . . . . . 40 Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Presence of Gravity . . . . . . . . . . . . . . . . . . . . . . . . 42 6Making a Spring and a Spring Balance . . . . . . . . . . . . . 43 Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Automatic Flushing Tank . . . . . . . . . . . . . . . . . . . . 46 Cartesian Diver . . . . . . . . . . . . . . . . . . . . . . . . . . 47 A Siphon . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 Liquid Pressure and Depth . . . . . . . . . . . . . . . . . . . . 50 Making a Magdeburg Hemisphere . . . . . . . . . . . . . . . . 52 Air Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54 The E ect of Surface Area on Pressure . . . . . . . . . . . . . 55 Light . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57 Light in a Straight Line . . . . . . . . . . . . . . . . . . . . . 57 Pin Hole Camera . . . . . . . . . . . . . . . . . . . . . . . . . 58 Laws of Re ection . . . . . . . . . . . . . . . . . . . . . . . . 60 3 Physics Activities for Form II 62 Static Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 Concept of Static Electricity . . . . . . . . . . . . . . . . . . . 62 Construction of an Electroscope . . . . . . . . . . . . . . . . . 63 Detection of Charges . . . . . . . . . . . . . . . . . . . . . . . 66 Current Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Conductors and Insulators . . . . . . . . . . . . . . . . . . . . 67 Finding Electric Circuit Components . . . . . . . . . . . . . . 68 Measuring Emf of a Cell . . . . . . . . . . . . . . . . . . . . . 70 Magnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Magnetic and Non-magnetic Materials . . . . . . . . . . . . . 72 Magnetic Fields . . . . . . . . . . . . . . . . . . . . . . . . . . 73 Earth's Magnetic Field . . . . . . . . . . . . . . . . . . . . . . . . . 75 Creating a Simple Compass . . . . . . . . . . . . . . . . . . . 75 Magnetic Dip Gauge . . . . . . . . . . . . . . . . . . . . . . . 77 Newton's Laws and Forces . . . . . . . . . . . . . . . . . . . . . . . 79 Inertia and Newton's First Law of Motion . . . . . . . . . . . 79 Conservation of Linear Momentum . . . . . . . . . . . . . . . 80 Bottle Rocket . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 Matchstick Rocket . . . . . . . . . . . . . . . . . . . . . . . . 84 Veri cation of Newton's First Law of Motion . . . . . . . . . . 87 Rotation and Equilibrium . . . . . . . . . . . . . . . . . . . . . . . 88 Centre of Gravity . . . . . . . . . . . . . . . . . . . . . . . . . 88 Veri cation of the Principle of Moments . . . . . . . . . . . . 90 Simple Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 Pulley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91 74 Physics Activities for Form III 95 Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Concept of Friction . . . . . . . . . . . . . . . . . . . . . . . . 95 Limiting Friction and the Coecient of Static Friction . . . . 96 Re ection of light . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Total Internal Re ection in Water . . . . . . . . . . . . . . . . 99 Refraction and Colour . . . . . . . . . . . . . . . . . . . . . . . . . 100 Dispersion of White Light: Part 1 . . . . . . . . . . . . . . . . 100 Newton Colour Wheel . . . . . . . . . . . . . . . . . . . . . . 102 Measuring Refractive Index of Glass . . . . . . . . . . . . . . . 104 Refraction of Light in Glass . . . . . . . . . . . . . . . . . . . 108 Heat Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Designing a Calorimeter . . . . . . . . . . . . . . . . . . . . . 110 Heat Conduction . . . . . . . . . . . . . . . . . . . . . . . . . 111 Convection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114 Radiation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 Thermal Expansion . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Bimetallic Strip . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Thermal Expansion of Gases . . . . . . . . . . . . . . . . . . . 121 Thermal Expansion of Solids - Breaking Glass . . . . . . . . . 123 Thermal Expansion of Liquids . . . . . . . . . . . . . . . . . . 124 Thermal Switch . . . . . . . . . . . . . . . . . . . . . . . . . . 127 Change of State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 Boiling at Room Temperature . . . . . . . . . . . . . . . . . . 129 Heat Capacity and Latent Heat . . . . . . . . . . . . . . . . . . . . 131 Latent Heat of Fusion . . . . . . . . . . . . . . . . . . . . . . 131 Vapour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133 Measuring Humidity with a Hygrometer . . . . . . . . . . . . 133 Gas Laws . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Boyle's Law . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Charles's Law . . . . . . . . . . . . . . . . . . . . . . . . . . . 137 5 Physics Activities for Form IV 140 Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 Creating a Leclanche Cell. . . . . . . . . . . . . . . . . . . . . 140 Construction of a Metre bridge and Potentiometer . . . . . . . 142 Creating a Light Bulb . . . . . . . . . . . . . . . . . . . . . . 146 Fuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 Making an Electric Heater . . . . . . . . . . . . . . . . . . . . 149 Inverter: Converting DC to AC . . . . . . . . . . . . . . . . . 151 Semiconductors and Semiconductor Devices . . . . . . . . . . . . . 157 8Forward and Reverse Biased Diodes . . . . . . . . . . . . . . . 157 Full-Wave Recti er . . . . . . . . . . . . . . . . . . . . . . . . 159 Half-Wave Recti er . . . . . . . . . . . . . . . . . . . . . . . . 162 Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 Construction and Use of Slinky Spring . . . . . . . . . . . . . 165 Construction of a Ripple Tank . . . . . . . . . . . . . . . . . . 167 Behaviour of Waves . . . . . . . . . . . . . . . . . . . . . . . . 169 Sound . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 Construction and Use of a Simple Sonometer . . . . . . . . . . 171 Wave Propagation in Solids . . . . . . . . . . . . . . . . . . . 173 Sound Ampli er . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Determination of Resonance Frequency . . . . . . . . . . . . . 176 Speed of Sound in Air . . . . . . . . . . . . . . . . . . . . . . 178 Electromagnetism . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Simple Motor . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Construction of Galvanometer . . . . . . . . . . . . . . . . . . 183 Force on a Current-Carrying Wire in a Magnetic Field . . . . 185 Water Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Wind Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Astronomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Solar System Mobile . . . . . . . . . . . . . . . . . . . . . . . 194 Star Gazing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 195 9Chapter 1 Laboratory Equipment Throughout this book you will see materials that have been marked with an asterisk (). These are locally available materials which can be made or purchased for your laboratory. The guide for using and making these local materials are found in the following section. Beakers Use: To hold liquids Materials: Water bottles, juice containers, lids for bottles or jars, and a knife Procedure: Take empty plastic battles of di erent sizes. Cut them in half. The base can be used as a beaker. Delivery Tube Use: For the movement and collection of gases, capillary tubes, hydraulic press Materials: Straws, pen tubes, or pawpaw petioles Needles Use: Compass needles, optical pins, making holes, ying wire Materials: Oce pins, sewing needles, needles from syringes Droppers Use: To add small amounts of liquid to something Materials: 2 mL syringes Procedure: Take a syringe. Remove the needle. 10Funnel Use: To guide liquid or powder into a small opening Materials: Empty water bottles Procedure: Take an empty water bottle and remove the cap. Cut them in half. The upper part of the bottle can be used as a funnel. Heat Source Use: Heating substances Materials: Candles, kerosene stoves, charcoal burners, or a moto poa stove Procedure: Cut a metal can in half and add a small amount of moto poa Stopper Use: To cover the mouth of a bottle, hold a capillary tube Materials: Rubber, cork, plastic water bottle cap Procedure: Cut a circular piece of rubber. If the stopper is being used to hold a capillary tube, a hole can be melted in a plastic cap or rubber stopper. Water Bath Use: To heat substances without using a direct ame Materials: Heat source, water, and a cooking pot Procedure: Bring water to a boil in a small aluminium pot, then place the test tubes in the water to heat the substance inside the test tube. Circuit Components Use: Building simple circuits, Ohm's Law, ampli er, wave recti ers Materials: Broken radio, computer, stereo, other electrical devices Procedure: Remove resistors, capacitors, transistors, diodes, motors, wires, transformers, inductors, rheostats, pulleys, gears, battery holders, switches, speakers and other components from the devices. Masses Use: Calibrating and using beam balance and spring balance, Hooke's Law Materials: Known masses, beam balance, sand, stones, plastic bags, thread, paper, tape, pen Procedure: Use a beam balance and known masses at a duka or nearby school to measure exact masses of sand or stones. Use a marker pen to mark the 11masses on the stones. If using sand, place a small piece of plastic bag on the scale pan and ll it with sand until you have the required mass. Tie the sand in the plastic bag with thread. Use paper and tape to make a label on the outside, marking the mass with pen. These masses can be used in your school. Water can also be as a known mass. The density of water is 1.0 g/mL, so you can use a known volume of water in a bottle to create a known mass. Be sure to also account for the mass of the bottle. Plane Mirror Use: Laws of Re ection, periscope, water prism Materials: piece of thin glass, kibatari, Optional: small pieces of mirror glass are cheap or free at a glass cutter's shop Procedure: Light the kibatari so that it creates a lot of smoke. Pass one side of the glass repeatedly over the kibatari until that side is totally black. The other side acts as a mirror. Iron Filings Use: To map magnetic elds Materials: Steel wool / Iron wool used for cleaning pots Procedure: Rub some steel wool between your thumb and ngers. The small pieces that fall are iron lings. Collect them in a matchbox or other container to use again. Checking Voltmeters and Ammeters/Galvanometers Needed: Meters to check, a couple of wires, some resistors and a fresh battery. Important note: There is a wrong way to hook up the meter. The needle will try to detect down because negative and positive are swapped. If the reading is zero, make sure that you try the opposite connection to be sure. Voltmeters Hook up the voltmeter across the battery. The battery is probably 1.5 V, but do not worry if you see 1.1, 1.2, even if using a brand new battery. Try not to use a battery that reads much below 1 V on several di erent meters. 12Unusable Voltmeters  Totally dead, no detection of the needle  Voltage reading jumps excessively. Ensure that the connections are solid and test again.  Measured voltage is totally wrong, not close to 1.5 V Usable Voltmeters  Read a voltage close to 1.5  If the voltage if not 1.5 exactly, the voltmeter is probably working and the battery is just old a bit. Ammeters Hook up the ammeter in series with a resistor. Because you do not necessarily know the condition of the ammeter before testing, be sure to have several di erent resistors on hand. An ammeter may appear not to work if resistance is too high or too low. Start testing di erent ammeters. Unusable Ammeters  Totally dead, no detection of the needle  Current reading jumps excessively (but check connections)  Totally wrong, reads much di erent from other ammeters Usable Ammeters Reads a current similar to other ammeters. Hard to say exactly what current, but feel free to calculate based on your resistor using V=IR, although do not forget that there is some internal re- sistance r of battery, so V = I(R + r). The resistance of the resistor is usually coded on the resistor in a series in stripes - see the instructions under Resistors in the Sources of Equipment section. Tip: You can hold the wires onto the battery with your ngers; the current is far too low to cause a shock. Other: Now that you have tested to see if your voltmeters and ammeters 13work, you can feel free to check all of them for accuracy, by calculating ex- pected values and comparing between meters. Most practicals will still work alright with somewhat accurate meters. 14Chapter 2 Physics Activities for Form I Measurement Construction of a Metre Rule Learning Objective  To construct and use a metre rule. Background Information Length is an interval between two points. It is usually measured in metric units like the metre (m), millimetre (mm), centimetre (cm), kilometre (km). Materials Wooden board, pen/pencil, a handsaw, ruler or tape measure Preparation Procedure 1. Use the saw to cut a piece of wood 100 cm x 3.5 cm x 0.5 cm. 2. Use a ruler to mark a scale in cm on the wood. Activity Procedure Use the new metre ruler to measure length of di erent objects. Discussion Question What other objects can be arranged in order to measure distance? 15Notes Instead of a wooden block, string can be used by making knots at a de nite intervals. Construction of a Measuring Cylinder Learning Objective  To construct and use a measuring cylinder. Background Information A measuring cylinders measures the volume of liquids in millilitres (mL). Materials Plastic bottles of di erent sizes, syringes (30-50 mL), marker pen, ruler, bucket full of water Preparation Procedure 1. Using the syringe, take a known volume of water from the bucket. 2. Transfer the known volume of water in the syringe to the empty plastic bottle. 3. Using the marker pen, mark the level of water in the plastic bottle with the volume from the syringe. 4. Repeat this step for a range of volumes, marking each volume on the side of the bottle. 5. Use a ruler to complete the scale. Activity Procedure Use the constructed measuring cylinder to measure volumes of di erent liq- uids. Clean Up Procedure Remove waste and return materials to their proper places. 16Discussion Question Explain how to use a measuring cylinder. Notes A measuring cylinder cannot be used to measure the volume of a solid by it- self, though if the solid is immersed in a liquid, the volume can be determined with a measuring cylinder. The volume of granular and porous materials can also be measured if they are immersed in a liquid in a measuring cylinder. Construction of Beam Balance Learning Objective  To construct and use a beam balance. Background Information Mass is a fundamental quantity and is measured by using a beam balance. In physics mass is usually measured in grams (g) or kilograms (kg). Materials Wooden bar 30 cm x 2 cm, string/wire, ruler, pencil/pen, 2 large plastic bottles, nails, heat source Preparation Procedure 1. Cut a piece of wood block to 30 cm x 2 cm. 2. Find the balancing point and then mark the point using a pencil or pen. 3. Make a hole at the balance point using a hot nail. 4. Mark 5 cm spaces on each side of the hole using a ruler. 5. Cut 2 plastic bottles about 3 - 4 cm from the bottom. 6. Make 3 round holes in the bottom of a plastic bottle at equal intervals. These will be used as scale pans. 7. Tie pieces of thread/wire about 15 cm length into the holes of the bottom of a plastic bottle. 17String Plane Wood String Strings Plastic Bottle Base Figure 2.1: A beam balance 8. Join the upper ends of the thread/wires together. 9. Suspend the wooden block by using a piece of string/wire tied through the centre hole. Activity Procedure Use the beam balance to measure the masses of di erent objects in the class- room. Clean Up Procedure Return all materials to their proper places. Discussion Question How can you improve the beam balance? 18Notes There are di erent kinds of balances, such as a digital balance, double beam balance, single beam balance and triple beam balance. Each can be used to measure mass according to its sensitivity. Measurement Errors Learning Objectives  To understand the meaning of experimental error  To understand the importance of accurate measurement and sample size Background Information Measurement is one of the most important aspects of science. However, it is impossible to make a perfect measurement because of our own errors and errors in the tools that we use. To improve our accuracy, we take many measurements and compare them to get an average result. However, it is important to understand the source of errors, how to account for them and how to reduce them. Di erent people measure di erently, and even one person will measure di erently from one moment to another. Materials Metre rules, stopwatches, other measuring instruments, materials to measure Preparation Procedure Collect di erent tools used for measuring, like metre rules or rulers, stop- watches, syringes, etc. Activity Procedure 1. Draw a line on the board or oor. 2. Have several students measure the line and secretly record their results. 3. Collect the results from the students and record them on the board. Observe any di erences. 4. Distribute stopwatches to several students. 19

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