Math Lab Activity

Edited byDouglas K. Brumbaugh

andMichael C. Hynes

Florida Technological UniversityOrlando, Florida 32816

CLASSROOM PHOTOGRAPHYRobert C. Bird

Florida Technological UniversityOrlando, Florida 32816

GOAL: The magic of photography has strong appeal for children of allages. The use of cameras in the classroom has been found to be veryhelpful in developing learning motivation and may be used by inno-vative teachers to bring together areas of study such as languagearts, social studies, science and mathematics. The following is a simplified procedure based on an EDC project called "Kids, Camerasand Communities" designed by Betty Merrill and James Parsons(1). This procedure makes it easy, manageable, and inexpensive totake photographs, develop film, and print pictures in an ordinaryclassroom.

OBJECTIVES: While doing this activity the student will:(a) Estimate distances between the object being photographed and

the camera he is using,(b) take pictures of objects which illustrate geometic shapes,(c) be involved in tactile experiences with geometric objects,(d) mix chemicals according to a given ratio,(e) measure temperatures in degrees Celsius,(f) measure time in seconds and minutes,(g) follow sequential steps as in arithmetic algorithms,(h) perform metric linear measurements,

and (i) calculate the ratio of the actual size of an object and the size ofthe same object in the developed film.

GRADES: Five through nineMATERIALS:

(a) Cameras: these may be obtained from Visual MotivationsCompany, Regal Road, King of Prussia. PA. 19406. This cam-era has simplicity as its main feature and uses 126 cartridgefilm. Another possible source of camera would be old, but usa-ble, box cameras that parents might donate to the school, orwhich may be purchased inexpensively at garage sales or FleaMarkets.

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Math Lab Activity 441

(b) A light-proof bag: light-proof bags can be made using threethicknesses of plastic garbage bags, open at both ends, andlined with cloth. The cloth lining is necessary to keep the filmfrom sticking to the plastic garbage bag while in the process ofloading the tank developer.

(c) Two short pieces of rope.(d) A roll-film tank developer with plastic aprons (such as Koda-

craft Roll-Film Tank): this tank developer uses a plastic apronrather than a reel and children as young as those in upper ele-mentary grades can load the developer themselves.

(e) Developer.(f) Fixer.(g) Five plastic pails.(h) A glass sandwich: the glass sandwich is a piece of glass and

cardboard taped together like a book. Its purpose is to hold thenegative and printing paper together.

(i) A pair of scissors.and (j) Studio proof paper: this type of paper is used because it is sen-

sitive to ultra violet light and needs no further chemicals todevelop the print.

PROCEDURES: The students are given film and a camera and are askedto take pictures of geometric shapes. After exposing the film the stu-dents follow the six steps of the development process and the threesteps in printing pictures. Examples of other picture taking activitiesmight include story-telling with photographs, sequencing photo-graphs that have obvious chronological order, development of spa-tial awareness, and picture poetry (2).

COMMENTS: Most frequently when I conduct this activity in the publicschools, the students will take the photographs on the first day. Thesecond day the film is developed and hung up to dry. On the thirdday the pictures are printed. If you wish to do this all in one day, Isuggest that the picture taking and developing be done in the morn-ing. This will allow the film to hang dry during lunchtime. Theprinting then can be done in the afternoon. The whole process(including picture taking, but not the drying time) can be done inabout 1 Vi hours.

442School Science and Mathematics

CLASSROOM PHOTOGRAPHY

After the photographs have been taken, the exposed film is loaded intothe tank developer inside the light-proof bag. One hand is placed ineach open end of the bag and the hands are tied into the bag so thatno light can enter the bag and ruin the film. After loading the tank,the top of the tank developer should be taped with masking tape toprevent the top of the tank from accidentally falling off in thefollowing steps of developing.STEP 1. RINSE. Use a cup to fill the tank with water. Shake

gently for one minute, then pour the water back intothe same pail. The purpose of this first rinse is to wetthe film to prepare it for the developing step.

STEP 2. Fill the tank with DEVELOPER. The developer shouldbe at 20 C. If the developer is too warm it will be over-active; if it is too cold, its action will be too slow. Shakegently for one minute, then shake periodically for 4more minutes. The developer should be in the tank fora total of five minutes. Pour the developer back into thesame pail. Black-and-white film is made on a plasticbase that supports an emulsion which contains light-sensitive silver salts. The salts on the film that werestruck by light are changed by the developer into metal-lic silver. The exposed areas of the film become dark,the greater the exposure to light the greater the change.

STEP 3. Fill the tank with WATER. Shake gently for one min-ute and empty the water back into the same pail. Wateris added here as a stop bath; this removes the developerso it will not make the exposed areas too dark.

STEP 4. Fill the tank with FIXER. Shake gently for one minute,then shake every once in a while for 4 more minutes.Keep the fixer in the tank for a total of five minutes.Pour the fixer back into the same pail. The fixing bathdissolves the unexposed salts so that they can be washedaway. This is necessary because these unexposed saltsare still sensitive to light.

STEP 5. WASH. Fill the tank with water and shake gently forabout one minute. Empty the water back into the samepail. Washing the film in water removes the unexposedsalts. These unexposed areas of the film become trans-parent. Washing also removes the chemicals of the fix-ing bath.

STEP 6. Hang up the film to DRY. Do not touch the film until itis completely dry. When the film is dry you are readyfor printing.

Math Lab Activity 443

There are three steps in printing.STEP 1. Indoors, away from the sunlight, cut a square of studio

proof paper just a little bigger than the size of the nega-tive.

STEP 2. Open the glass sandwich and place the square of studioproof paper on the cardboard, shiny side up. Place thenegative on the proof paper shiny side up and close theglass.

STEP 3. Place the glass sandwich in the sunlight, so that the sunshines through the negative onto the paper, leave in thesunlight for about thirty seconds. When the edges ofthe paper turn dark purple, the print should be ready.

REFERENCES

1. MERRILL, B. and PARSON, J., The Shutterbug-Book Two, Model Cities Pilot Schools,Baltimore, Md., 1971.

2. FURTH, H.G. and WACHS, H., Thinking Goes To School, Oxford University Press, NewYork,1975.

CONTINENTAL GROWTH RATE

A Columbia University geologist, reading the record of a rare form of oxygenin cores of sediment drilled from the ocean bottom, has calculated that the con-tinents have grown 5 to 40 percent over the past three billion years and are stillgrowing.The reported continental growth rates were inferred from measurements of

oxygen-18 at various levels of the thousand-foot-long cores. While otherscientists have suggested that the continents are growing, the Columbia study isthe first to calculate the rate of increase.

Geologists have long observed that the interiors of most continents contain themost ancient rock, which is surrounded by younger geologic formations. (Aus-tralia is one exception, its "core" of oldest rock being located on its westernedge, which, some 200 million years ago, drifted free from the center of the"supercontinent" (Gondwanaland.) Some scientists believe that the continents’combined size has remained constant, the younger portions simply being con-tinental material recycled by various geologic processes. Others, however, viewthe rocks’ differing ages as evidence that the continents are actually growing insize. Dr. Lawrence said that his analyses of oxygen-18 fluctuations lend strongsupport to that second viewpoint.

1979 Annual SSMA ConventionKansas City

November 1-3,1979