Place Value within 50 - One more one less - Presentation

In a mathematics lesson focused on place value within 50, primary school children are introduced to the concept of finding 'one more' or 'one less' than a given number. The lesson employs a variety of resources such as tens frames and base 10 blocks to help pupils visually grasp the concepts of incrementing or decrementing a number by one. For example, when presented with the number 23 using base 10 blocks, students are asked to determine what one less than 23 is. Through hands-on activities, they discover that removing one block results in the number 22. Similarly, when starting with the number 30, adding one more block increases the count to 31, illustrating the concept of 'one more'.

Further activities encourage children to use tens frames and counters to build numbers and then find 'one more' or 'one less'. When working with the number 25, students are shown that adding one counter to the tens frame results in 26, while removing a counter from a tens frame of 11 leads to the number 10. These exercises reinforce understanding through visual and tactile learning. The lesson also includes reasoning challenges where children must deduce a number based on a description, such as finding a number that is one more than 18 or determining Rosie's number, which has four tens and would change the tens digit if decreased by one. Discussions prompt critical thinking about the direction of counting for 'one more' or 'one less', which digit changes, and how to verify the correctness of their answers.