To effectively differentiate instruction for using multiple means of representation in a first-grade mathematics lesson on addition and subtraction within 20, I can employ the following strategies: 1. Interactive Activities- engage Richard with hands-on activities that require movement. This can help him focus and maintain interest in the lesson. 2. Technology-Based Tools- utilize education software or apps that provide interactive and engaging ways to practice addition and subtraction. These tools often include visual and auditory elements that can help Richard understand and apply the concepts 3. Challanging Tasks- since Richard is a gifted student, he may need more challenging tasks to keep him engaged. Provide problems that require higher-order thinking skills. For example, give him a set of numbers and ask hom to create his own addition and subtraction. 4. Frequent Breaks- given Richard has ADHD, he may benefit from short frequent breaks summize