Research has established that children's development of addition and subtraction skills progresses through a hierarchy of strategies that begin with counting-by-one methods through to flexible mental strategies using a combination of knowledge of basic facts and understanding of place value. An important transition point is the shift from the counting-by-one strategy for addition to a variety of strategies that do not rely on counting by ones. Assisting the child to develop sophisticated non-count-by-one strategies, such as doubling, also supports a child's progression through the ideas of equal grouping and skip-counting to multiplication and division. According to McIntosh (2004), encouraging students to concentrate on the mental computation strategies they use for counting, can lead to enhanced confidence in handling numbers and understanding place value. This article presents three complete lesson ideas designed to introduce and develop young children's confidence in the computation strategies associated with doubling numbers. The lessons also aim to develop children's problem-solving and working-mathematically skills, particularly skills in recording using drawings, numerals, symbols, and words. (Contains 2 figures.)