Addition and subtraction within 20 - Subtraction crossing 10 2 - Starter

In a Year 1 mathematics lesson, students are encouraged to master addition and subtraction within 20, focusing on subtraction problems that involve crossing the number 10. The lesson starts with a 'Fluent in Four' revision segment, where students are presented with subtraction problems such as "19 – 13" and "20 – half of 20", which they solve to practice their fluency in basic arithmetic operations. The exercises are designed to reinforce mental subtraction skills and the concept of halving numbers.

The lesson continues with a practical application using a number line to help visualise the subtraction process. For example, students are asked to complete the calculation "14 – 6" by marking the numbers on the number line and counting backwards to find the answer. Additionally, the lesson includes a comparative measurement activity where students determine who is the tallest between two individuals, Tia and Rosie, by comparing the number of cubes next to their names. In a probability exercise, students explore the possible outcomes of a dice game. They are given the scenario of Zach rolling two dice to score a total of 6, while Leanna scores less with one die showing a 3. Students are asked to deduce the other number Leanna could have rolled, considering that there may be more than one solution.