L6 Spring Missing Number Problems within 20

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A Year 1 maths lesson on adding a one-digit number to a two-digit number using counting on. Includes active outdoor starter, number line activities, and reflection on efficient addition strategies.
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This engaging Year 1 maths lesson helps children develop confidence in adding a one-digit number to a two-digit number (within 20) using the counting-on method. The lesson begins with a lively starter where pupils use frog jumps on a number line to visualise addition, reinforcing earlier learning from Year 1 Spring 1. Taking the activity outside, children physically jump along a number line to count on from a given number, supporting kinaesthetic learning and number fluency. In the main teaching input, pupils explore how addition can be done in any order and learn the importance of starting with the larger number when counting on to make calculations more efficient. Using number lines, counters, and practical examples such as 14 + 4, children see how to move along the number line and record their findings. During the activity, pupils create and solve their own addition sentences by selecting random number cards (10–20) and rolling a 10-sided die. They record number sentences in their books and practise efficient counting strategies. The plenary encourages reflection on when counting on is most effective, helping children understand that while it works well for smaller numbers, other strategies may be needed for larger ones. This resource promotes hands-on, active learning and builds conceptual understanding of addition, number patterns, and efficiency in mental calculation.
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