Addition and subtraction within 20 - Subtraction not crossing 10 - Presentation

In a series of engaging activities designed for young learners, the concept of subtraction within 20 is explored, specifically focusing on scenarios where the subtraction does not require crossing the number 10. The lesson begins with a discussion on the meaning of subtraction and its synonyms, setting the stage for practical application. One of the key activities involves a scenario where there are 16 biscuits on a plate, and Malachi eats 5 of them. Students are prompted to complete sentences to reflect the change in the number of biscuits, using the subtraction sentence 16 - 5 to find the answer. This activity not only reinforces subtraction skills but also encourages the understanding of 'first, then, now' sequences in problem-solving.

Further activities include the use of ten frames and counters to visually represent subtraction problems, such as when 9 sheep run away or 3 birds fly off, leaving none behind. These visual aids are particularly helpful for children to grasp the concept of subtraction as 'taking away'. Additionally, the lesson incorporates the use of a number line to complete number sentences, which aids in the visualisation of the subtraction process and provides a clear method for calculating answers to problems like 20 - 7 or 19 - 3. The lesson concludes with reasoning activities that challenge students to apply their understanding of subtraction to various problems and to articulate their thought processes, thereby deepening their mathematical comprehension.