Ray's New Practical Arithmetic · Arts. 131–134 · Unit 11: Decimal Fractions
63. What decimals are
Goal: Your child explains decimal places as tenths, hundredths and thousandths continuing the place-value pattern to the right of the units.
You'll need
- The book
- A slate, small whiteboard or scrap paper
- A notebook and pencil
What's in the book
Decimal fractions: the orders of integers continued to the right of the unit, the decimal point, a diagram of places on both sides of the unit, definitions, and how a denominator of 10, 100 or 1000 decides the number of decimal places.
The lesson, step by step
Warm-up
Ask: How much is a dime of a dollar? (1/10.) A cent? (1/100.)
Continuing the pattern
Read:
The orders of integers decrease from left to right in a tenfold ratio.
The orders may be continued from the order units toward the right by the same law of decrease.
Let the order units be separated from the order that follows by a point (.).
Both sides of the unit
Read:
The first order on the left of the unit is tens, the first order on the right of the unit is tenths;
Draw a place-value chart: thousands, hundreds, tens, units | tenths, hundredths, thousandths.
Definitions
Read:
A decimal fraction, or decimal, is one or more tenths, hundredths, thousandths, etc.,
A decimal point ( . ) is placed before the order tenths to distinguish the fraction.
Counting places
Read:
Hence, when the denominator is 10, there is one decimal order.
Hence, when the denominator is 100, there are two decimal orders.
Write 3/10 = .3, 3/100 = .03, 3/1000 = .003.
Wrap-up
Ask: How do you write 7 hundredths? (.07.) 7 thousandths? (.007.) What is $3.25 in dollars, dimes and cents?