Lesson 14 In this lesson, children use mental methods and estimation to support calculations. They will learn that sometimes mental strategies should be used over formal methods. There is a teaching presentation accompanied by differentiated activities with a range of fluency, reasoning and problem-solving questions.   Year 6 Mathematics Content Descriptors   V8.4 Select and apply efficient mental and written strategies and appropriate digital technologies to solve problems involving all four operations with whole numbers ACMNA123   V9 use mathematical modelling to solve practical problems involving natural and rational numbers and percentages, including in financial contexts; formulate the problems, choosing operations and efficient calculation strategies, and using digital tools where appropriate; interpret and communicate solutions in terms of the situation, justifying the choices made AC9M6N09   Differentiation: There are three levels of differentiation in this pack: ‘working towards,’ ‘expected’ and ‘greater depth’.Level of this Pack: Age: 11-12 Australia: Grade 6  ...