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

In a comprehensive lesson aimed at mastering addition and subtraction within 20, the focus is on the skill of subtracting numbers without crossing the ten boundary, using the method of counting back. The lesson utilises fluency and reasoning teaching slides to guide students through the process. A number line is introduced as a visual aid to facilitate understanding of subtraction by counting backwards. Students are encouraged to discuss how a number line can be a helpful tool in visualising and solving subtraction problems.

Diving into the activities, the students are presented with a practical scenario involving subtraction that does not cross ten. For instance, if there are 16 sweets in a jar and Rosie eats 4, students are prompted to use a number line to determine how many sweets are left. By counting back from 16 to 12 on the number line, they can easily see that Rosie has 12 sweets remaining. Further exercises include similar subtraction problems, such as 17 minus 6 and 15 minus 2, with students using the number line to find the answers, which are 11 and 13 respectively. The lesson progresses to independent work where students are tasked with using the number line to count back and write the answers to given calculations, reinforcing their subtraction skills within the range of 20.