CONTRACT PLAN in HIGH-SCHOOL CHEMISTRY J. 0. FRANK State Teachen' College, Oshkosh, Wiswnsin
On the C level, the pupils' activities will be widely Though much has been written about the "contract" or 'yoiob" plan of teaching, little is available in the way directed by the teacher; on the B level, they will be parof exact accounts of its use in the teaching of chemistry. tially directed by the teacher's suggestions. On the A I n the following artick the writer explains the theory upon level, the pupil will be expected to find the problems, which the plan is based, describes i n detail the plan itself, find a way to solve them, and to carry his work to comand furnishes a n original "contract" which may be pletion in a well-organized and effectivereport. copied or reprinted for use in high-school classes. The objectives of the complete contract, on the highest level, include the development of: (1) understandings of the more important facts; (2) increased ability to read and understand the assignment, see the probN MODERN life, the intelligent individual has lems involved, and devise ways of attack upon them; to be able to find and interpret facts, rather than (3) the drive to carry forward intelligently the activito carry facts in his memory. It is now impossible ties needed in the solution of the problems; and (4) for anyone to understand all of the facts and forces that increased ability to organize, interpret, and present may affect him-but it i s possible and necessary for the the evidence discovered and the conclusious reached. intelligent individual to know how to learn all important This plan will be successful only to the degree facts which affect him in a given situation and to know to which the pupils make progress toward complete and how to interpret them and to make proper use of them intelligent sey-direction and the attitude of active interin the solution of his problems. est in all necessary activities. The contract plan of teaching is intended to be used Rewards sbould be distributed on the basis of: in such a way as to produce situations and present prob- (1)ability in independent thinking shown, (2) quality of lems similar to those of everyday life as far as possible. accomplishment, and (3) quantity of accomplishment. It is intended that the pupil shall learn through his During the past decade, much has been written own activities, self-directed as far as his ability will about the contract plan of teaching high-school chempermit, and that these activities shall always be directly related to real problems. No "busy work" need istry. Some teachers, who have used the contract plan, are enthusiastic about it; while others have not be assigned in a well-organized and properly prepared found it an effective scheme of teaching. I t seems probcontract. On the other hand, it is conceded that pupils able that the way in which it is d e d , the conditions must be taught bow to work and must be given practice under which it is used, and the familiarity of the teacher in sustained application in the accomplishment of with the contract plan all have much to do with the some worthwhile task. teacher's success. In using the contract plan, the teacher's function is The writer is convinced that the plan can be used much the same as in other plans of teaching: effectively in many schools where poor or ineffective (A) Bringing the pupils to want to learn. schemes are now in operation, and therefore attempts (B) Providing suitable learning exercises* here to describe a "contract" in high-school chemistry (1) On the C level, the fundament& of the unit. and edplain how it may be used effectively. Since (2) On the B level, additional items providing nitrogen, sulfur, calcium, and a few other units have for more personal responsibility and more already been written up as "contracts," another unit, "Aluminum," is chosen to illustrate this article. extended experience. To make as clear as possible just how the teacher and (3) On the A level, problems which will permit entire personal responsibility and provide the students work together, under the "contract" plan. for the play of creative thought, inventive the unit will be presented so that "Directions to Teachability, and the use of the scientific method. ers" and also the actual "contract" given to the pupils (C) Providing adequate means of determining pupil may be mimeographed for school use. Tests for use accomplishment and securing sustained and active with this contract may be devised by the teacher, or copies will be furnished gratis by the writer. pupil interest and cooperation.
I
(From the results obtained, the teacher decides whether one or two more days are needed, plans accordingly, and notifies pupils.)
THE ALUMINUM CONTRACT
(A Unit in Elementary Chemi~try) (4 or 5 days)
5th Class Period. F . COMPLETION OF THE CONTRACT.
The use of this unit will be effective only in classes where the teacher and the pupils have a working understanding of the contract plan.
A continuation of work by pupils on contract, or pupil reports before the class on various phases of the contract may be in order. If some pupils have completed the A contract, they may help pupils who are still on the C contract.
I d Class Period
A. TEEEXPLORATION. The teacher, by means of questions or problems, tests the understanding of the pupils regarding the most important features of the unit ( i . c.. the imDortance of aluminum in modern life. its chemical a i d ohvsi'cal nature. and the orac. tical user of aluminum products). The purpose is to arowr intwrar, to c h a l h n g ~applic3tiun. to prt avlivc pnrtivipation in the prcst.nration, and t o find a n y major dcficirncies in foundation. (5 to 10 minutes.) B. TEE PRESENTATIONOR S T ~ A T ~ O N . The teacher presents an overview of the unit, giving general information, showing importance of aluminum, aluminum salts. and aluminum alloys. This is a direct attempt t o "sell" the h i t to the pupils-to get them interested, t o make them feel that they have a fair start on the "job" or "contract." Incarryingout this part of the presentation, the teacher should use maps; charts; slides; movies; exhibits; samples of minerals, manufactured products, and aluminum salts; and in fact anything and everything which will help in developing interest and in giving the pupils a general understanding of the essential items (objectives) of the aluminum unit. (20 to 25 minutes.)
Last Class Period.
.
G. FINALTEST OF RESULTSACCOMPLISHED AND AWARDOW HONORS. A new-type examination covering the C. B, and A levels of the contract will be given. Grades will be awarded according to the work accomplished hy the pupils. Some teachers will give another day for remedial teaching or re-teaching. (As the result of this, another short test may he given and further adjustments in grades made.) Some teachers will use self-grading tests (or pupils will do grading) and complete this contract in 5 class periods.
Best Additional References (Several references are given in the directions to pupils.) (1) J. CHEM.EDUC.,7, pp. 233, 245, 2376, 2383 (1930); 8, pp. 182. 613, 689, 743, 933, 1015 (1931). (2) "A short story of aluminum." Aluminum Goods Mfg. Co.. Manitowoc, Wis. Free. (3) Booklet, "Combating chemical corrosion." Aluminum Company of America, Pittsburgh. Pa. Free.
Best Visuel Aids The teacher now passes out the mimeographed "contracts" which the pupils read through a t once. The pupils ask questions if they care to do so. Questions may be asked concerning: the meaning of any part of the contract; sources of information; methods of procedure: method of writing up the report: or anything else which is not understood. (This bears a close resemblance to supervised study in its best form.) (10 t o 20 minutes.)
(1) 22 slides on aluminum (up-to-date and accurate), also' an accompanying booklet, W. M. Welch Scientific Company, 1516 Orleans Street, Chicago. Ill. (2) Movie, "Chemical effects of electricity." 16 mm. One reel. Eastman Teaching Films, 343 State Street, Rochester, N. Y. Cost $30.00. (May be rented.) 43) Samples and Exhibits:
2nd end 3rd Chss Periods. D. INVESTIGATION, ORGANIZATION, ASSIMILATION, APPLICATION. Pupils work in classroom, library, and laboratory (and sometimes make trips to factory, plant, or museum) carrying on the investigations outlined in the contract; weighing the evidence; writing down tentative conclusions; discussing evidence and tentative conclusions with classmates; performing experiments t o test conclusions reached; and preparing a report to show the work accomplished. The teacher assists pupils in finding and interpreting evidence; acts as judge in discussions; inspires pupils to further endeavor; encourages when necessary; guides on grcursions; and a t all times acts as general overseer of all activities. (All this work is informal. Pupils keep a record of their own time and of work accomplished. The teacher, however, may ask for a report showing progress a t any time.)
4th Class Period. E. P~E~rnrrsanv TESTING OR ACCOMPLISHMENT. (Recitation or Discussion.) The teacher calls a meeting of the class for preliminary discussion of difficulties encountered and results accomplished. There is also a brief oral or written quiz. (Mast pupils have completed the C contract by this time.) Then pupils continue their work on the contract. (15 to 45 minutes.)
a. Exhibit, pamphlet, and pictures.
Aluminum Goods Mfg. Co., Manitowoc, Wis. Free. b. Obtain locally three or four different kinds of clay. (Give formulas and probable impurities.) c. Photographs showing process of making porcelain or china ware. The Coors Company, Golden, Colo. Free. d. Booklets and possibly an exhibit. Aluminum Company of America, Pittsburgh, Pa.
.................................................
.......
(To be given to the pupils in mimeographed form) THE
ALUMMUM CONTRACT (ORU N I ~ ) ~
Aluminum is the mast abundant of all the metals in the earth's crust. Because of the widely varied properties of the metal and its alloys and the wide usefulness of its compounds, it is one of the most important of all of the chemical elements. The chief objectives t o be attained as the results of the teaching outlined in this contract are as follows:
1. T o understand where and how aluminum occurs in nature. 2. T o understand how the metal is obtained from the ore. 3. T o gain an understanding of the properties and uses of the metal and its alloys. 4. To gain an understanding of the properties and uses of the most important compounds of aluminum. 5. To gain an appreciation of the importance of aluminum. aluminum alloys, and aluminum compounds in modern life.
Best References DULL. C. E.,"Modern chemistry," Henry Halt & Co., New York City, 1931, p. 364. $1.80. FRANKAND WRITE, "High-school science terminology," W. M. Welch Co.. Chicago, Ill., 1930, p. 9. 82.50. H o ~ ~ sH., s , "Introductory college chemistry," The Macmillan Co., New York City. 1931, p. 477. $3.50. MCPHBRSON. HENDERSON, AND FOWLER,"Chemistry for $1.80. todav." G -- & & Co..Boston. Mass., 1930. p. 462. HOPKINS,B. s., " ~ e & r a l ch&istry for iilleges," D. C. Heath & Co., Boston, Mass., 1930, PP. 64%9. G.50. "Development and use of baking powder," U. S. Dept. Agriculture. Circular 138 (Nav., 1930). U. S. Go*. Printing Office, Washington, D. C. $0.05. B-R. L. H., "Metals . -. .that we-eat." -- H y g k , 9,33-9 (Jan.. 1931). Am. Med. Assoc. SU:da. EDDY,W. H., "Metals in our foods," Good Housekeeping, 89, 96 (Oct., 1929). $0.25. RBPORT,"Aluminum utensils," Sci. Am., 144,1974 (1931).
.-,
~~~~
(5) (6) (7) (8) (9)
..
an .m w"."".
(10) RASK,0. S., "An introductory story of baking powders," J. CDM. Enuc., 9, 1340-57 (Aug., 1932). $0.50.
"C" or "Fair" Contract (Minimum Essentials)
-
Am=> ,-+,.-fi -->",
12
By reading, laboratory experiments, or other investigation, prepare answers t o the followingquestions and carry out the other activities requested. Make rough notes of your results as you assemble data. Finally prepare a report in the form of a plan for ,,Aluminum and Its pmductsu as it a thirty-minute talk might he given before a high-school science club, before a women's club, or a business men's dub. Draw up a plan showing just how you would give this talk. (You may use equations, outline drawings, charts, or diagrams, if any of these will help you show the place and importance of aluminum in our modern civilization.) Use a notebook and enter all data or information just as you find it, not afterward. The followingquestions and problems are given to assist you in gathering and evaluating the necessary data. Qzreslwns and Problems
1. List the five most common minerals containing aluminum. Give formulas for these and indicate the percentage of aluminum in each. 2. Give the percentage of each of the five most abundant melds in the earth's crust. 3. Why do we not extract aluminum from clay? Why was aluminum not used until recent years? 4. Draw a rough map of North America in your notebaok, olltline the states which have produced aluminum ore in commercial quantities, and mark the centers where metallic aluminum is prepared from the ore. 5. Give the properties and uses of three different varieties of aluminum oxide. What is the percentage 6f aluminum in purr aluminum oxide? 6. Where is crwlite obtained and what is its chemical formula? Explain by means of a lettered diagram the apparatus and method by which aluminum is obtained from bauxite. Make a table of important events in the history of aluminum, ~i~~ at least five important dates and eventsand three important names. Why isn't bauxite reduced with carbon as are many other oxides? Metallic aluminum is widely used in the electrical industries. Give a t least three reasons for this. 11. What properties of aluminum cause it to be widely used in the manufacture of toys and small objects of all kinds?
12. Chemists consider aluminum to be almost an ideal metal for the manufacture of cooking utensils. Give six properties of the metal which lead t o this conclusion. What properties of aluminum make i t a desirable metal for the manufacture of oil tanks? Why are steel tanks often painted with aluminum paint? Why are factory interiors often painted with aluminum paint? Why should radia t m not be painted with aluminum paint? 14. Why is aluminum paint especially useful as a priming coat on new houses? 15. Explain by means of a diagram the use of powdered metallic aluminum in the "themite" welding process. Give the equation involved and explain how the high temperature is obtained. 16, ~ ~the use l of metallic e ~aluminum in obtaining metallic chromium, manganese, etc. 17. Large quantities of metallic aluminum are used in the making of steel. Explain. 18. The remarkable permanence of the luster of metallic aluminum is said to be due to the formation of a very thin coat of the oxide which protects the metal from all further attack. Compare aluminum and iron in this remect. 19. Airship girders of durolumin are now coated yith pure metallic aluminum. Why? 20. Give the composition, properties, and two uses of magnalium. Why is this alloy not more widely used? 21. Give the composition, properties, and five uses of duralumin. Give three reasons why this alloy is used in constantly increasing amounts. What is meant by heat treatment of an alloy. 22. Give the composition, properties, and two uses of aluminum bronze. 23. Place a small strip of aluminum in a test-tube, cover with dilute HCI and heat gently for 2 minutes. Pour the liquid into a beaker. cool, and make alkaline with NHIOH. Write the equations showing the reactions involved. 24. Place a small strip of aluminum in a test-tube, cover with dilute NaOH, and boil gently for 2 minutes. Pour the liquid into a beaker and cool, make acid with HNOs and then alkaline with NH40H. Explain using equations. 25. What is meant by the term "amphoteric" hydroxide? 26. Dissolve 5 g. of powdered AL(SO& crystals in 100 cc. of water. Test of this solution with litmus paper. Explain. To 5 cc. of the solution, add lime water until the solution is alkaline. What is the precipitate formed? Add some dust or mud to the remainder of the A1&OI)I solution. Now add enough lime water to mak; distinctly alkaline, mix thoroughly, pour into a measuring cylinder or tall beaker, and let stand overnight, Give the fundamental facts regarding the use of Ab(S04)rin the clarification of water. 27. Mix same dry powdered A1dS0JS with some dry NaHCOa. Add water to the mixture. Bubble the gas into lime water. Explain. Explain the "Foamite" fire'extinguisher. 28. Explain the meaning of the word "alum." What are the four essential parts of an "alum"? Write the formula for potassium alum. 29. Anhydrous sodium aluminum sulfate is an ingredient of the so-called combination baking powders. Explain how C% is liberated from the soda. 30. The use of anhydrous sodium aluniinum sulfate produces a baking powder which is comparatively slow in its action, the Con being released during the baking process. Why? Alum is not used in baking powders because i t would be too rapid in action and the COI would be released before the baking process w a s well begun. Why? If baking powders were made from alum, they would not retain th& strength. Why? Explain the r81; of starch as an ingredient of baking powder.
31. Calculate the amounts of NaHCOs and anhydrous sodium aluminum sulfate required t o make one pound of baking powder yielding 14% of C02.
44. It is said that aluminum ranks fifth in importance among the metals. What metals are more important than aluminum and why?
32. Calculate the weight of hydrated Aln(SO')s and of ( N H d 8 0 1 required t o make 20 g. of ammonium alum. Weigh out required amounts of these salts, dissolve in the least possible amount of hot water and let stand overnight. Note color and shape of crystals. 33. Boil a piece of clean white cotton cloth in very dilute HC1 to remove the sizing. Cut into one-inch strips. R i s e thoroughly. Dye a piece of this cloth by boiling 3 minutes with a dilute picricacid solution. Dyeanother piece in a similar manner with methyl orange solution. Dye similar pieces of white woolen cloth in the same manner. Try to wash the dye from each piece of cloth. Explain.
45. I l a k a list of the twenty must useful ohjcctr you can think of which may he made of aluminum or aluminum alloys. (Sce J. CIIFY.EDUC.,9, 834-9 ( h h y , 1032).1 46. Write and illustrate with diagrams and cuts a brief account of the manufacture of artificial rubies giving all essentials of the process. What is artificial corundum? What is "aluudum"? Where are these used?
34. Boil a strip of clean cotton cloth for 3 minutes in a beaker containing a 5% solution of AIz(SOJn. Remove the cloth, cool, and wring nearly dry. Now dip the cloth into a hot solution of dilute NH40H and wring nearly dry again. What has been precipitated in the fibers of the cloth? What is a mordant? 35. Boil the strip of mordanted cloth, prepared in 34 above, for 5 minutes in 25 cc. of a solution containing 1 g. of alizarin in 100 cc. of water. Boil in the same solution a strip of unmordanted cloth. Try t o wash both pieces of cloth free from the dye. Explain. 36. Explain the terms "direct dyes" and "mordant dyes." 37. What are "lakes"? How are they prepared? 38. Explain the importance of silicate of aluminum in the manufacture of brick, pottery, chinaware, and cement. When you have finished the work on the "C" contract. refer again to the list of objectives of the study of aluminum. Summarize your work and discuss i t with others in the class. When you are sure of all of your facts, make a brief summary under each objective. Make a list of questions you would like to ask if the teacher calls the class together for discussion. Submit your report t o the teacher in charge. If it is approved, begin the "B" contract a t once. "B" or "Good" Contract This is not to be started until the "C" contract has been entirely finished. I t includes all of the "C" contract and also the following, presented in the form of a written report:
39. Prepare a list of charts, maps, tables, diagrams, display of samples, pictures, etc., such as you would like to use in vitalizing and making effective such a talk as outlined above in the "C" contract. Describe briefly each of the above maps, charts, etc., which you would use. 40. Explain the steps in the mining and refining of alumina. 41. How much aluminum by weight might be obtained from a ton of bauxite which w a s 60% pure alumi,na?
When you have finished the work of the "B" contract. submit your report to the teacher in charge. When it is approved, proceed a t once with the work of the " A contract.
"A" or "Ezcellent" Contract This is not begun until all the work on the "B" contract has been completed. It includes all of the "B" contract and also one of the fol!owing:
47. Actually give a talk of fifteen minutes or more, on aluminum, before your class or a group of ten or more people using the plan and the illustrative materials which you prepared under the "C" and "B" contracts. or 48. Prepare tables, diagrams, and all necessaty equations which are needed t o explain the composition and reactions involved in the use of the three important types of baking powder: a. Tartrate. 6. Phosphate. c. Combination. (Sodium aluminum sulfate and calcium acid phosphate.) 49. Prepare a written report on the use of aluminum silicate in the industries. Be sure that your report covers the fundamentals of the manufacture of bricks, pottery, porcelain, chinaware, and cement. or 50. The most important aluminum salts from a commercial standpoint are: Alum (potassium and ammonium), used as mordants, fire-proofing of fabrics, etc. Aluminum chloride (anhydrous), used in organic synthesis (Friedel-Kraft reaction) and in the cracking of oils. Aluminum sulfate, used in purifying, water and the . sizing of paper. Sodium aluminum sulfate (anhydrous), used in the manufacture of baking powders. Explain in a written report how the aluminum salts mentioned are used in one of the processes mentioned, giving all quantitative relations and demonstrating with actual samples.
.
Aluminum has about oue-third the density of copper. Compare the weight and size of wires of copper and aluminum of equal electrical conductivity.
When you have finished the work of the "A" contract, carefully review all the work you have done an aluminum as a preparation for a test covering the entire unit. You may attempt that part of the test covering the "B" and "A" contracts only after your work a t these levels has been approved by the teacher in charge. Youi final grade indicates the quality and quantity of your accomplishment.
The following articles on the subject of aluminum have appeared in the JOURNAL OF CKEMICAL EDUCATION: 1. H o ~ s s ,"Some commercial applications of aluminum," 7, 245-56 (Feb.. 1930). 2. HOLMES, "The story of aluminum," 7,23%44 (Feb., 1932). 3. HOWARD,sapphire^," 8, 613-24 (Apr., 1931). 4. M~APEE,"The manufacture of commercial anhydrous
aluminum chloride," 7, 2376-82 (Oct., 1930). 5. M~ARDLE,"Aluminum utility exemplified in a modem research laboratory," 9,83C9 (May. 1932). 6. PORTER,"Aluminum in the south," 7,2383-6 (Oct., 1930). 7. WADE,"Man-made gems," 8,1015-26 (June, 1931). 8. See also WEEKS,"The discovery of the elements. XII," 9, 1396 (Aug.. 1932).
42. Using a diagram, explain the Hoopes process for refining aluminum.
*
43. The electrical conductivity of aluminum is about 60y0 that
..
of annealed coooer. -
