Missing Addends Math Drills Within 20 Grade 1 – Valentine Theme | 20 Pages with Answer Key Help students build a strong understanding of addition with this Valentine-themed missing addends math drills pack! This resource supports Grade 1 students in finding the unknown addend while practicing addition within 20, helping develop number sense, reasoning, and fluency. Perfect for math centers, morning work, intervention, homework, fast finishers, assessments, and Valentine’s Day math activities.