Addition and subtraction - Subtract a three-digit number from a three-digit number no exchange - Presentation

In a comprehensive lesson geared towards enhancing fluency and reasoning in subtraction, students are challenged to subtract three-digit numbers from three-digit numbers without the need for exchange (or regrouping). The lesson underscores the importance of aligning place value columns correctly to ensure accurate calculations. Students are engaged through a variety of activities, starting with the use of bar models to find missing values and progressing to more complex tasks. For example, they might be presented with the number of children in a school and asked to determine how many are boys based on the number of girls, or to calculate how many children have packed lunches given the number having school dinners. These activities require careful placement of hundreds, tens, and ones on a place value grid to perform subtraction.

Further activities include column subtraction exercises where students are prompted to fill in the blanks with the correct numbers. These exercises serve to reinforce the concept of subtracting without exchange. In addition, reasoning tasks challenge students to explore multiple methods of reaching the correct answer, such as finding different ways to represent a number using counters, or determining possible solutions when given certain conditions like odd digits in shaded boxes. The lesson concludes with independent work where students can use number lines, word problems, and Base 10 blocks to practice and demonstrate their understanding. Throughout the lesson, students are encouraged to discuss their strategies and ways to verify the correctness of their answers, prompting deeper understanding of the subtraction process.