Instructional Sequence for Addition and Subtraction Operations of Decimals

Digits of numbers must be added according to their place values.
Digits of numbers must be subtracted according to their place values.
Decimals are another way of writing fractions
Base ten is infinite in both directions
Decimal point can represent "and" when reading decimal numbers.
Decimal point locates the units position.

Prior knowledge

Heard of percent

Background information

Number value is the foundation of operations.
Students should be able to estimate to determine a reasonable answer.

Sequence of ideas

Whole number place value is connected to decimal number place value
Role of the decimal point
Base ten infinitely large and small
Connect fractions to decimals, decimals are another way of writing fractions - base ten fractions
Explore rational numbers with models
Use friendly numbers (tenths, hundredths, thousandths and percent) for addition and subtraction
Include numbers greater than and less than one
Use friendly numbers (tenths, .25, .5, .50, .75) for multiplication. Invent whole numbers times tenths are tenths, whole numbers times hundredths are hundredths, tenths times tenths are hundredths.
Use friendly numbers for division - There are 12 people and 10 subs. How much subs do each person get? do multiple ways.
Generalize a rule for multiplication and division based on base ten.

Activity/Strategy

Review whole number place value

writem read, and say numbers activity

Role of the decimal point

smiley face decimal

Base ten infinitely large and small

strip and square (10x10) model
make a chart of 100

Connect fractions to decimals, decimals are another way of writing fractions - base ten fractions

fraction to decimal
decimal to fraction

Use friendly numbers (tenths, hundredths, thousandths and percent) for addition and subtraction Include numbers greater than and less than one

strip and square (10x10) model
make a chart of 100
no money or use money to explore decimals
meter stick
circular disks

Use friendly numbers (tenths, .25, .5, .50, .75) for multiplication. Invent whole numbers times tenths are tenths, whole numbers times hundredths are hundredths, tenths times tenths are hundredths. Include numbers greater than and less than one

strip and square (10x10) model
make a chart of 100
no money or use money to explore decimals
meter stick
circular disks

Use friendly numbers for division - There are 12 people and 10 subs. How much subs do each person get? do multiple ways. Include numbers greater than and less than one

strip and square (10x10) model
make a chart of 100
no money or use money to explore decimals
meter stick
circular disks

Generalize a rule for multiplication and division based on base ten. Include numbers greater than and less than one

strip and square (10x10) model
make a chart of 100
no money or use money to explore decimals
meter stick
circular disks

Real world problems with whole, fraction, and decimal numbers to apply all above.

literary connections