Christian S. Gle Prof. Josseme Tendido-CastroBEEd 3A

SCIENCE MATERIALS AND EQUIPMENTS INSIDE THE PRESCHOOL CLASSROOM

Objectives:At the end of the lesson, the student will be able to:

Introduce different materials and equipments inside the preschool classroom Demonstrate the different uses of science equipments

Subject Matter:Topic: Science Materials and Equipments inside the Preschool ClassroomReference: Wikipedia.com, slideshare.netMaterials: visual aids, handouts, science materials

Lesson Content:

1. Science Materials or Laboratory Apparatus

i. Beaker – is a simple container for stirring, mixing and heating liquids commonly used in many laboratories. Beakers are generally cylindrical in shape, with a flat bottom and a lip for pouring.

ii. Test tube – also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top, usually with a rounded U-shaped bottom. Hold a small experiment, which would be used to conduct an investigation.

iii. Florence flask – has a round body with a single long neck and with either a round or a flat bottom. It can be used as a container to hold solutions of chemicals. It is designed for uniform heating and ease of swirling; it is produced in a number of different glass thicknesses to stand different types of use.

iv. Erlenmeyer flask – also known as a conical flask, is a widely used type of laboratory flask which features a flat bottom, a conical body, and a cylindrical neck. Erlenmeyer flasks are suitable for heating liquids. The small neck reduces evaporative losses compared to a beaker, while the flat bottom of the conical flask makes it unlikely to tip over and spill.

v. Graduated cylinder – is a piece of laboratory equipment used to accurately measure the volume of a liquid. Water displacement can be used to find out the volume of a solid. Graduated cylinders are generally more accurate and precise for this purpose than flasks and beakers.

vi. Funnel – is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel, spillage would occur.

vii. Watch Glass – funnel is a pipe with a wide, often conical mouth and a narrow stem. It is used to channel liquid or fine-grained substances into containers with a small opening. Without a funnel, spillage would occur.

viii. Evaporating dish – is a laboratory device for evaporation of solids and supernatant fluids, and sometimes to their melting point. Evaporating dishes are used to evaporate excess water - or other solvents - to ensure that a concentrated solution or the dissolved substance is left behind.

ix. Crucible and cover – A crucible is a ceramic container capable of withstanding extreme temperatures, whilst the cover is designed to prevent heat escaping from the crucible itself. Crucibles are used for a range of purposes, and are particularly common amongst chemists for the chemical analysis of various substances.

x. Bunsen burner – device for combining a flammable gas with controlled amounts of air before ignition; it produces a hotter flame than would be possible using the ambient air and gas alone.

xi. Iron clamp – An iron clamp is a piece of laboratory equipment used to hold things and is placed in an iron stand to elevate other equipment.

xii. Iron stand – A metal rod attached to a heavy metal base. The heavy base keeps the stand stable, and the vertical metal rod allows for easy height adjustment of the iron ring/clamp. (A tripod can sometimes be used in place of an iron stand.)

xiii. Iron Ring – An iron ring that holds glassware such as a funnels or other objects, like the wire gauze or clay triangle for heating with a Bunsen burner. Often, the iron ring will be attached to an iron stand. 

xiv. Test tube holder – The test tube holder obviously is designed to hold test tubes. However, it can be used to hold pipettes and stirring rods, etc. as well.

xv. Test tube brush – It is a device, made with nylon bristles attached to a twisted-wire shaft, used to knock the bottoms out of test tubes. It is a brush that is long and narrow to clean the inside of glassware, in particular test tubes. 

xvi. Wire Gauge – The use of wire gauze in an experiment is to place under the container holding the liquid that is being heated by the Bunsen burner, so that the container doesn't have direct contact with the flame.

xvii. Tripod – is a three-legged equipment, generally used as a platform of some sort. This lab equipment is used to support and hold various flasks, beakers and other glass ware when not in use and also during experiments.

xviii. Spatula – is used to take and handle small quantities of solid chemicals. It is used like a spoon or an instrument for scooping material out of a container. 

xix. Stirring rod – is a piece of laboratory equipment used to mix chemicals and liquids for laboratory purposes. They are usually made of solid glass, about the thickness and slightly longer than a drinking straw.

xx. Mortar and Pestle – is a tool used to crush, grind, and mix solid substances. The substance to be ground is placed in the mortar and ground, crushed or mixed with the pestle.

xxi. Medicine dropper – is an instrument used to measure small amount of liquids, usually in milligrams.

xxii. Test tube racks – is a convenient and necessary piece of laboratory equipment for the storage of test tubes.

xxiii. Microscope – is an instrument used to see objects that are too small for the naked eye. There are many types of microscopes, the most common and first to be invented is the optical microscope which uses light to image the sample.

xxiv. Triple beam balance – is a type of balance commonly used in the laboratory to determine the mass of samples. To use the balance, you use sliding weights called riders on three beams, each with progressively small incremental amounts. 

xxv. Pipette – is a laboratory tool used to transport a measured volume of liquid. It is also use to extract or deliver small amounts of liquid.

xxvi. Burette – is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap. It is used to dispense known amounts of a liquid reagent in experiments.

xxvii. Platform balance – The platform balance is a form of equal-arm balance in which two flat platforms are attached to the top side of the beam, one at each end.

xxviii. Alcohol lamp – are usually found in biology labs where they do inoculations of bacteria cultures. It heats the wire loop on a stick that they use to spread the bacteria on the growth medium, which will prevent contamination to the cultures.

xxix. Aspirator – is also known as an eductor-jet pump, or a filter pump. T his is a device that is able to produce a vacuum by using the venture effect. In an aspirator there is a fluid that flows through a narrowing tube. Once the tube starts narrowing, the fluid's speed is able to increase.

xxx. Tongs – are used to hold many different things such as flasks, crucibles, and evaporating dishes when they are hot.

xxxi. Volumetric flask – is a piece of laboratory glassware, a type of laboratory flask, used in analytical chemistry for the preparation of solutions. Are used for making up solutions to a known volume.

xxxii. Spring balance – is simply a spring fixed at one end with a hook to attach an object at the other. A spring balance measures the weight of an object by opposing the force of gravity with the force of an extended spring.

2. Magnifying Glass

A magnifying glass (called a hand lens in laboratory contexts) is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle (see image).

A sheet magnifier consists of many very narrow concentric ring-shaped lenses, such that the combination acts as a single lens but is much thinner. This arrangement is known as aFresnel lens.

The magnifying glass is an icon of detective fiction, particularly that of Sherlock Holmes.

History

The earliest evidence of "a magnifying device, a convex lens forming a magnified image" was Aristophanes's "lens", from 424 BC, a glass globe filled with water. (Seneca wrote that it could be used to read letters "no matter how small or dim").[1] Roger Bacon described the properties of a magnifying glass in 13th-century England. Eyeglasses were developed in 13th-century Italy.

Magnification

The magnification of a magnifying glass depends upon where it is placed between the user's eye and the object being viewed, and the total distance between them. The magnifying poweris equivalent to angular magnification (this should not be confused with optical power, which is a different quantity). The magnifying power is the ratio of the sizes of the images formed on the user's retina with and without the lens.[3] For the "without" case, it is typically assumed that the user would bring the object as close to the eye as possible without it becoming blurry. This point, known as the near point, varies with age. In a young child it can be as close as 5 cm, while in an elderly person it may be as far as one or two metres. Magnifiers are typically characterized using a "standard" value of 0.25 m.

The highest magnifying power is obtained by putting the lens very close to the eye and moving the eye and the lens together to obtain the best focus. The object will then typically also be close to the lens. The magnifying power obtained in this condition is MP0 = (0.25 m)Φ + 1, where Φ is the optical power in dioptres, and the factor of 0.25 m represents the assumed near point (¼ m from the eye). This value of the magnifying power is the one normally used to characterize magnifiers. It is typically denoted "m×", where m = MP0. This is sometimes called the total power of the magnifier (again, not to be confused with optical power).

Magnifiers are not always used as described above, however. It is much more comfortable to put the magnifier close to the object (one focal length away). The eye can then be a larger distance away, and a good image can be obtained very easily; the focus is not very sensitive to the eye's exact position. The magnifying power in this case is roughly MP = (0.25 m)Φ.

A typical magnifying glass might have a focal length of 25 cm, corresponding to an optical power of 4 dioptres. Such a magnifier would be sold as a "2×" magnifier. In actual use,

an observer with "typical" eyes would obtain a magnifying power between 1 and 2, depending on where lens is held.

Using this principle, a magnifying glass can also be used to focus light, such as to concentrate the sun's radiation to create a hot spot at the focus.

3. Large Stool Magnifier or Tripod Magnifier

The tripod magnifier (Fig. 1) is a simple lens mounted on a mechanical stand. The tripod is placed over the object and the focus is obtained by means of a screw which raises or lowers the lens, according to the degree it is magnified.

4. Weighing Scales

Weighing scales (usually just "scales" in UK and Australian English, "weighing machine" in south Asian English or "scale" in US English) is a measuring instrument for determining the weight or mass of an object. Weighing scales are used in many industrial and commercial applications, and products from feathers to loaded tractor-trailers are sold by weight. Specialized medical scales and bathroom scales are used to measure the body weight of human beings.

Balance Scales

The balance (also balance scale, beam balance and laboratory balance) was the first mass measuring instrument invented. In its traditional form, it consists of a pivoted horizontal lever of equal length arms, called the beam, with a weighing pan, also called scale, scalepan, or bason (obsolete), suspended from each arm (which is the origin of the originally plural term "scales" for a weighing instrument). The unknown mass is placed in one pan, and standard masses are added to the other pan until the beam is as close to equilibrium as possible. In precision balances, a slider mass is moved along a graduated scale. The slider position gives a fine correction to the mass value. Although a balance technically compares weights, not masses, the weight of an object is proportional to its mass, and the standard weights used with balances are usually labeled in mass units.

Balances are used for precision mass measurement, because unlike spring scales their accuracy is not affected by differences in the local gravity, which can vary by almost 0.5% at different locations on Earth. A change in the strength of the gravitational field caused by moving the balance will not change the measured mass, because themoments of force on either side of the balance beam are affected equally. In fact, a balance will measure the correct mass even on other planets or moons, or any location that experiences a constant gravity or acceleration.

Very precise measurements are achieved by ensuring that the balance's fulcrum is essentially friction-free (a knife edge is the traditional solution), by attaching a pointer to the beam which amplifies any deviation from a balance position; and finally by using the lever principle, which allows fractional masses to be applied bymovement of a small

mass along the measuring arm of the beam, as described above. For greatest accuracy, there needs to be an allowance for the buoyancy in air, whose effect depends on the densities of the masses involved.

The original form of a balance consisted of a beam with a fulcrum at its center. For highest accuracy, the fulcrum would consist of a sharp V-shaped pivot seated in a shallower V-shaped bearing. To determine the mass of the object, a combination of reference masses was hung on one end of the beam while the object of unknown mass was hung on the other end (see balance and steelyard balance). For high precision work, the center beam balance is still one of the most accurate technologies available and is commonly used for calibrating test weights.

To reduce the need for large reference masses, an off-center beam can be used. A balance with an off-center beam can be almost as accurate as a scale with a center beam, but the off-center beam requires special reference masses and cannot be intrinsically checked for accuracy by simply swapping the contents of the pans as a center-beam balance can. To reduce the need for small graduated reference masses, a sliding weight called a poise can be installed so that it can be positioned along a calibrated scale. A poise adds further intricacies to the calibration procedure, since the exact mass of the poise must be adjusted to the exact lever ratio of the beam.

For greater convenience in placing large and awkward loads, a platform can be floated on a cantilever beam system which brings the proportional force to a noseiron bearing; this pulls on a stilyard rod to transmit the reduced force to a conveniently sized beam. One still sees this design in portable beam balances of 500 kg capacity which are commonly used in harsh environments without electricity, as well as in the lighter duty mechanical bathroom scale (which actually uses a spring scale, internally). The additional pivots and bearings all reduce the accuracy and complicate calibration; the float system must be corrected for corner errors before the span is corrected by adjusting the balance beam and poise. Such systems are typically accurate to at best 1/10,000 of their capacity, unless they are expensively engineered.

Some mechanical balances also use dials (with counterbalancing masses instead of springs), a hybrid design with some of the accuracy advantages of the poise and beam but the convenience of a dial reading.

SymbolismThe scales (specifically, a two pan, beam balance) are one of the traditional symbols of justice, as wielded by statues of Lady Justice. This corresponds to the use in metaphor of matters being "held in the balance". It has its origins in ancient Egyp

Scales are also the symbol for the astrological sign Libra.

History

The balance scale is such a simple device that its usage likely far predates the evidence. What have allowed archaeologists to link artifacts to weighing scales are the stones for determining absolute weight. The balance scale itself was probably used to determine relative weight long before absolute weight.

The oldest evidence for the existence of weighing scales dates to c. 2400-1800 B.C.E. in the Indus River valley (modern-day Pakistan). Before then no banking was performed due to lack of scales. Uniform, polished stone cubes discovered in early settlements were probably used as weight-setting stones in balance scales. Although the cubes bear no markings, their weights are multiples of a common denominator. The cubes are made of many different kinds of stones with varying densities. Clearly their weight, not their size or other characteristics, was a factor in sculpting these cubes. In Egypt, scales can be traced to around 1878 B.C.E., but their usage probably extends much earlier. Carved stones bearing marks denoting weight and the Egyptian hieroglyphic symbol for gold have been discovered, which suggests that Egyptian merchants had been using an established system of weight measurement to catalog gold shipments and/or gold mine yields. Although no actual scales from this era have survived, many sets of weighing stones as well as murals depicting the use of balance scales suggest widespread usage.

Variations on the balance scale, including devices like the cheap and inaccurate bismar, began to see common usage by c. 400 B.C.E. by many small merchants and their customers. A plethora of scale varieties each boasting advantages and improvements over one another appear throughout recorded history, with such great inventors as Leonardo da Vinci lending a personal hand in their development.

Even with all the advances in weighing scale design and development, all scales until the seventeenth century C.E. were variations on the balance scale. Although records dating to the 1600s refer to spring scales for measuring weight, the earliest design for such a device dates to 1770 and credits Richard Salter, an early scale-maker Spring scales came into common usage in 1840 when R. W. Winfield developed the candlestick scale for use in measuring letters and packages. Postal workers could work more quickly with spring scales than balance scales because they could be read instantaneously and did not have to be carefully balanced with each measurement.

By the 1940s various electronic devices were being attached to these designs to make readings more accurate. These were not true digital scales as the actual measuring of weight still relied on springs and balances. Load cells, small nodes that convert pressure to a digital signal, have their beginnings as early as the late-nineteenth century, but it was not until the late-twentieth century that they became accurate enough for widespread usage.