Addition and subtraction within 20 - Subtraction crossing 10 counting back - Worksheet

The worksheet provides a series of subtraction exercises focusing on the concept of 'crossing 10' while counting back within the range of 20. This method is crucial for young learners as it helps them understand the process of subtracting numbers that require borrowing from the next tens place. The exercises begin with a number line that spans from 0 to 20, which serves as a visual aid for children to count back and find the answers to the given subtraction problems. The tasks include simple subtractions such as '13 – 6' and more challenging ones like '15 – 9', where the subtraction crosses the 10 boundary, necessitating the counting back method for accurate calculation.

As children progress, they move from using the number line to performing subtraction in their heads, which helps develop their mental arithmetic skills. The worksheet encourages students to become secure in counting back and to think critically about subtraction calculations that will result in specific answers. For instance, given the result '7', children are prompted to devise a subtraction problem that starts with a number between 11 and 19 and yields the given result. This exercise not only reinforces the concept of 'crossing 10' but also fosters a deeper understanding of the relationship between numbers in subtraction. The worksheet's structure is designed to build fluency and precision in young mathematicians as they master the curriculum.