These exercises, activities and games are designed for students to use independently or in small groups to practise number properties. Some involve investigation and should be formally written up (Investigation Write Up) and may become longer and more involved tasks with subsequent recording/reporting. Typically an exercise is a 10 to 15 minute activity.
double two digit numbers using mental strategies
Multiplication and Division, AM (Stage 7)
100s chart and flipblock 100s board
Practice excercises with answers (PDF or Word)
counters
calculator
Prior knowledge
Background
This activity involves doubling two digit numbers. Strategies for doubling numbers include
(1) use of place value e.g. 36 doubled is 60 + 12 = 72
(2) use of rounding e.g. 36 doubled is 35 + 35 + 1 + 1 or 40 + 40 - 4 - 4
(3) use factors e.g. 36 = 4 x 9 so 36 doubled in 8 x 9 = 72
The activity also uses equipement such as hundreds boards and number lines to double numbers.
Further information to back up what they will meet:
FIO Books – Check Number Books for doubling activities.
National Archive of Virtual Manipulatives (via Google)
Comments on these exercises
Exercise 1
Asks students to double a range of number form 2 - 175. Encourage the students to practise menatl startegies outlined in the Background.
Exercise 2
Asks students to double two and three digit numbers using hundreds boards.
Exercise 3
Asks students to double two and three digit numbers using a number line.
Exercise 4
Asks students to double two digit numbers in a dice game context.
Exercise 5
Asks students to double three digit numbers in a dice game context.
Exercise 6
Asks students to double three digit numbers using a mental strategy. in a dice game context.