Developed in conjunction with Lesley University, this engaging resource for first grade provides effective, research-based strategies to help teachers differentiate problem solving in the classroom. It includes: 50 leveled math problems (150 problems total), an overview of the problem-solving process, and ideas for formative assessment of students' problem-solving abilities. It also includes 50 mini-lessons and a student activity sheet featuring a problem tiered at three levels, plus digital resources that include electronic versions of activity sheets. This resource was developed with College and Career Readiness in mind, is aligned to the interdisciplinary themes from the Partnership for 21st Century Skills, and supports core concepts of STEM instruction.