Despite the intrinsic interdisciplinary nature of STEM, teaching interdisciplinarity in the classroom is difficult and students struggle to find the applicability of concepts and skills in different scientific disciplines. In this work we propose a micro-credential "badge" system called Demonstrated Understanding of Core Knowledge (DUCK) that is applicable to both biology and chemistry. A DUCK is a structured learning activity where students showcase their understanding of a specific concept or skill using videos. We present two categories of DUCKs, each reflecting a unique skill set: "Technical skill" DUCKs are based on hands-on and laboratory skills such as use of lab equipment, safety, and proficient execution of lab techniques, whereas "Analytical Skill" DUCKs focus on cognitive understanding and abilities, requiring intellectual application and critical thinking rather than physical execution. We have identified 25 Technical and 12 Analytical DUCKs. Out of the 25 Technical DUCKs, four are specific to biology, four to chemistry, and 17 are applicable to both the domains, whereas all the proposed 12 Analytical DUCKs can be applied to both biology and chemistry. This approach enhances interdisciplinary learning in introductory biology and chemistry labs, fostering a unified perspective on foundational lab skills that are applicable across scientific disciplines.