13. If there are scales in the schoolroom, weigh 12 lb. How many ounces in 12 lb.?

14. Pour into a paper bag what you think is a pound of sand. Now weigh the sand. By how many ounces is your estimate wrong? By what fraction of a pound are you wrong? By .what decimal part of a pound are you wrong?

15. Estimate 2 lb. and test your estimate. Also 5 lb.

16. Express as tons and decimals of a ton:

(3) 3550 lb.

(4) 12,500 lb.

(1) 3000 lb. (2) 5000 lb. 17. What will 3000 lb. of hay cost at $14 a ton? What will 2500 lb. cost? 3500 lb.?

are

18. 5 cwt. of mixed feed will last how many days, if 25 lb. used per day? If the cost is 80¢ per hundredweight, what is the cost per day?

21. 1 ounce = ? grains. lb. = ? grains.

22. If you should use only 1-oz. weights in weighing 5 lb. of sugar, how many weights would you put on the scales? How many, if you used a 3-lb. and a 2-lb. weight?

23. Three carloads of coal contain 37,623 lb., 33,526 lb., and 28,912 lb. respectively. How many tons do they contain together?

24. A wagon and its load of coal weigh 3750 lb. The wagon weighs 1200 lb. What is the coal worth at $6.50 a ton?

25. A cubic foot of water weighs 62 lb. How many ounces does it weigh?

26. 15 boxes weigh 50 lb. each. What fraction of a ton do they weigh together? What decimal fraction?

27. If a bushel of corn weighs 56 lb., how many bushels are there in a ton?

28. Find the difference between 5 long tons and 5 short tons.

29. If 20 long tons of coal are bought at $4.85 per ton and sold at $6.25 per short ton, what is the gain?

30. Make up and work an example similar to Ex. 18. To Ex. 23. Ex. 27.

31. Choose sides and solve an example in addition, dictated by the teacher, similar to Ex. 11, p. 23. The side wins which first passes in 10 correct papers.

EXERCISE 101

ORAL WORK

1. How many ounces in 1 lb.? In 3 lb.? lb.? lb.? lb.? ğ lb.?

2. How many pounds in 32 oz.? In 80 oz.? 3 cwt.? 1 ton? 4 tons? 3. How many ounces in 1 lb. 3 oz.? In 2 lb. 8 oz.? 3 lb.?

4. If a pound of butter costs 28 cents, what will 8 oz. cost? 4 oz.? 12 oz.? 2 lb. 4 oz.?

5. If a pound of coffee costs 36 cents, what will 22 lb. cost? 8 oz.? 3 lb. 12 oz.? lb.?

6. If a pint of water weighs a pound, and a glass of water is half a pint, how much does a glass of water weigh? glass? glass?

7. A certain bottle can be filled four times from a glass of water. How many ounces does the bottle hold?

8. How many tons in 1000 lb.?

In 6000 lb.? 60,000 lb.?

9. How many pounds in 6 tons? In 15 tons? 2 tons?

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10. When flour is 4 cents a pound, what will 2 cwt. cost? 8 oz.? 11. What will it cost to mail a book weighing 10 oz.? 18 oz.? 12 oz.? 12. State the cost of mailing a magazine weighing 6 oz. 12 oz.

13. What will it cost to mail a letter weighing 2 oz.? 3 oz.? 4 oz.? 14. How many of the examples in Exercise 100 can you work at sight?

MEASURES OF LENGTH

97. Linear Units is a general name for units of length (as one inch, one foot, one yard, etc.) as distinguished from units of area or of volume.

The foot is frequently divided into tenths and hundredths of a foot instead of into inches. Thus, instead of 2 ft. 6 in., we write 2.5 ft.

Instead of the contractions ft. and in., the signs' and " are frequently used. Thus, instead of 2 ft. 6 in., we write 2′ 6′′. The latter method is especially useful on diagrams, where the figures and signs should occupy as little space as possible.

Reduce:

1. 2 ft. 9 in. to inches.

EXERCISE 102

2. 3 yd. 2 ft. to feet. Also to inches.

3. 2 rd. 3 yd. to feet.

4. 3 mi. 100 rd. to rods.

5. 2 mi. 300 yd. to yards.

6. 2'7" to inches.

7. Show the meaning of Exs. 1, 2, and 6 with the foot rule.

14. Show the meaning of Exs. 8 and 9 with the foot rule.

15. How many yards long is the quarter-mile run? The halfmile run? Name some place which you think is mile away.

16. How many feet are there in 3 mile? In How many yards in each of these?

mile? mile?

17. How many feet in 4.28 miles? In 2.6 miles? How many yards in each of these?

18. If railroad ties on the average are 21 ft. apart, how many ties will be used in laying a mile of track? What will these cost at $.60 a tie?

19. How many shingles, each 4 in. wide and placed side by side, will be needed to make a row 24 ft. long?

20. Draw on the blackboard a line which you think is a yard long. Now measure this line. By how many inches are you wrong? By what fraction of a yard are you wrong?

21. Show on the side of the schoolroom the distance which you think is a rod. Test your guess by actual measurement.

22. Which is easier to use: the foot rule 33 times, or the rod measure twice? Which measurement is more likely to be accurate? What, then, are some uses of the rod measure?

23. Think of the length of the 100-yard dash (or some other distance 100 yards long). Now name a place which you think is 200 yd. from the schoolhouse. Also one 300 yd. distant.

24. Sound travels 1090 ft. per second. How many yards is this?

While the teacher counts" one - two" slowly, let your mind run over a distance nearly 4 times as long as the 100-yard dash. This will enable you to realize the velocity of sound.

25. If a railroad train travels 60 miles an hour, how many feet is this per second? (Group all operations and use cancellation.) How many yards? How does this velocity compare with the velocity of sound?

Visualize your answer by thinking the proper multiple of 100 yd., while the teacher counts one - two" slowly.

26. Let the teacher give examples in which a distance on a map or drawing is given, to find the scale.

27. A 12-inch cannon will send a cannon ball 20,000 yd. How many miles is this? (Compute the fraction to 3 decimal places.)

28. Name some place which you think is 1 mile distant. Also one 10 miles distant.

29. Measure the length of the schoolroom by using the foot rule repeatedly. Now measure it by use of the yard measure. Which method is easier? Why? Which is more likely to be accurate?

30. Walter can run the 100-yard dash in 12 seconds. The distance around the bases of the baseball diamond is 150 yd. (allowing for extra distance in turning corners). How long will it take Walter to run the bases when he makes a home run?

31. Make up and work an example similar to Ex. 1. To Ex. 9. Ex. 19.

32. How many examples in Exercises 60 and 61 (pp. 104, 106) can you now work at sight?