Ray's New Practical Arithmetic · Arts. 72–73 · Unit 7: Reduction of Compound Numbers
39. Miscellaneous tables optional
Goal: Your child reads the older tables (troy and apothecaries' weight, old lengths, circular measure, counting and paper) and does reductions with them.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
Troy weight, apothecaries' weight and fluid measure, old measures of length (hand, fathom, league, chain), circular measure in degrees, minutes and seconds, then tables of counting and paper, with problems 1 to 27. Answers are printed.
The lesson, step by step
Warm-up
Mental: How many in a dozen? In a score? How many degrees in a circle?
Troy weight
Read:
Troy Weight is used in weighing gold, silver, and jewels.
Note for you: troy ounces are still used for gold and silver prices. Apothecaries' weight (scruples and drams) is gone from use; read it once as history.
Old lengths
Read a few lines:
4 inches = 1 hand.
6 feet = 1 fathom.
3 miles = 1 league.
Horses are still measured in hands and water depth in fathoms.
Circular measure
Read:
Circular Measure is used in measuring circles.
Table: 60 seconds make 1 minute, 60 minutes 1 degree, 360 degrees a circle.
Guided practice
Together:
What is the height of a horse of 16½ hands?
A man is 4 score and 10: how old is he?
(66 in. = 5 ft. 6 in.; 90 years.)
Independent practice
Your child chooses about ten of problems 1 to 27, including some on degrees and some on dozens, quires and reams.
Check and wrap-up
Answers are printed. Ask: Why might a jeweler and a grocer use different pounds?
Tip
This guide is mostly history. Skim the apothecaries' and paper tables; spend the time on degrees and dozens.