Addition and subtraction - Three-digit and one-digit numbers not crossing 10 - Presentation

In Lesson 3, students are introduced to the concept of adding and subtracting one-digit numbers from three-digit numbers without crossing the boundary of ten. The lesson focuses on understanding the place value system and reinforces the concept that when adding or subtracting ones, only the ones column is affected, provided the sum or difference doesn't require regrouping. Students are encouraged to use place value counters to visually represent and solve the number sentences. For example, when subtracting 3 from 414, students learn to reduce the ones column by 3, resulting in 411, and similarly, adding 3 to 414 results in 417. The lesson's activities are designed to enhance fluency and reasoning skills in basic arithmetic operations.

The lesson progresses with various activities that require students to apply their knowledge. Activity 2 presents further practice with subtraction and addition, such as 225 minus 2 equals 223, and 225 plus 2 equals 227. In Activity 3, students are prompted to explain their methods and consider alternative ways to check their work, such as calculating, building with counters, drawing, and verbal explanation. They are also introduced to comparison symbols like 'greater than' (>), 'equal to' (=), and 'less than' (<), to compare quantities, as seen when comparing table points in a classroom context. Reasoning tasks challenge students to deduce possible starting numbers and operations based on given results, fostering critical thinking and pattern recognition. The lesson concludes with independent work where students engage in activities that test their understanding of the concepts taught.