Students use a range of visual representations to calculate the product of two digit numbers, including the distributive law, with a view to establishing efficient mental computation. After completing these exercises students compare these methods to traditional ‘long’ multiplication techniques.
Apply the associative, commutative and distributive laws to aid mental and written computation - ACMNA151.
Distributive law, units, tens, digit, product
About the Lesson
Starting with a visual representation (rectangle) for the product of two numbers students can step through the problem. The diagram uses colour, labels and numeric representation to link calculation steps. Students complete the calculations on the hand-out sheet and check their answers with a calculator. After completing the visual representation of the distributive law they work with a more symbolic approach and compare these methods with traditional ‘long multiplication’ methods. The objective is for students to develop efficient mental strategies to work with number.