Scouts and Guides Array
Visual of the marching scouts and guides from page 39.
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We can count the scouts and guides separately and add them, or add the rows first and multiply by the number in each row.
Understand and apply the distributive property to evaluate expressions efficiently.
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Introduction to the distributive property via the hotel bill example.
Lhamo and Norbu went to a hotel and ordered a vegetable cutlet (₹43) and a rasgulla (₹24) each. How do we write the total amount they pay?
Visual of the marching scouts and guides from page 39.
We can count the scouts and guides separately and add them, or add the rows first and multiply by the number in each row.
Worked example deriving the distributive property.
In a parade, boy scouts march in 4 rows with 5 scouts in each row. Girl guides march in 3 rows with 5 guides in each row. Calculate the total number of children in two different ways.
Formal statement of the distributive rule.
The multiple of a sum (or difference) is the same as the sum (or difference) of the multiples.
Faded practice applying the distributive rule.
Let's expand the expression using the distributive property. First, we apply the 7 to the first term inside the bracket: . Next, we apply the 7 to the second term inside the bracket, keeping the subtraction sign: . Putting it all together, the fully expanded expression is .
MCQ discriminating correct from incorrect distribution.
Which of the following mathematical statements is FALSE?
Introducing the use of distributive property for mental math.
Have you ever had to multiply large numbers in your head and found it tricky? We can use the distributive property to make difficult multiplications much easier!