Multiplication. Doughnuts

I bought 60 doughnuts and put them in a large tray.

Draw one way the tray may look? Write number sentences that match your tray.

Write number sentences for all the other ways the tray might look.          

Each doughnut cost $1.35. How much did the whole tray cost?         

(Multiplication Rubric)

Show your solution in pictures, numbers & words.

1.25

1.5

2.0

2.25

2.5

2.75

3.0

3.25

3.75

4.0

Drawing of diagrams to show sharing of up to 20 items

Counting by 2s, 5s and 10s from 0 to a given target.


Students describe and calculate simple multiplication as repeated addition, such as

 3 × 20

as 20 + 20 + 20; and division as sharing, such as 60 shared between 3.

 

They use commutative and associative properties of addition and multiplication in mental computation (for example,    40 + 20

= 20 + 40

and

30 + 20 + 10

can be done as

30 + 30.

 

Use of money as a model for grouping and unpacking lots of 10s.

Use of written number sentences such as

60 ÷ 3 = 20 to summarise sharing (partition) and ‘how many?’ (quotition) processes

 

Automatic recall of number facts from 2, 5 and 10 multiplication tables. (6 tens is 60)

Representation of multiplication as a rectangular array and as the area of a rectangle

Use of fact families to solve division problems, for example

3 × 20 = 60,

60 ÷ 3 = 20

 


Students compute with numbers up to 30 using all four operations.

They provide automatic recall of multiplication facts up to 10 × 10.

They devise and use written methods for whole number problems of addition and subtraction involving numbers up to 999; multiplication by single digits (using recall of multiplication tables) and multiples and powers of ten (for example,

5 × 100, 5 × 70 );

division by a single-digit divisor (based on inverse relations in multiplication tables).

 

Appropriate selection and use of mental and written algorithms to add, subtract, multiply and divide (by single digits) natural numbers

Multiplication of fractions by fractions through use of the rectangle area model diagrams.

Multiplication by increasing and decreasing by a factor of two; for example,

    60 × 1

 = 30 × 2

 = 15 × 4

and

    20 x 3

= 10 x 6

= 5 x 12.

Recognition that multiplication can either enlarge or reduce the magnitude of a number (multiplication by fractions or decimals) 60 x 35 cents will be less than $60.

Use of inverse relationship between multiplication and division to validate calculations


Students explain and use mental and written algorithms for the addition, subtraction, multiplication and division of natural numbers (positive whole numbers).

They add, subtract and multiply fractions and decimals (to two decimal places).Therefore calculate total cost 60 x $1.35 = $81 with working out shown.

 

 

Comments