**2. K-12 STEM education and twenty first century skills**

The National Education Association of the United States developed the *Framework for 21st Century Learning* in 2002 through a collaboration of educators, education

experts, and business leaders, with the goal of defining the skill set needed for success in work, life, and citizenship [16]. The framework consisted of 18 skills, which were further refined into four learning and innovation skills in 2012. Referred to as the Four C's, these skills include critical thinking, communication, collaboration, and creativity [17].

The Four C's are highlighted in many twenty first century skills (21CS) policy documents from around the globe, often including social and emotional intelligence, technological literacy, and problem-solving skills [18]. Education systems, both formal and informal, play a critical role in fostering development of 21CS. Joynes et al. [19] cited a broad range of literature discussing 21CSs, concluding that "there is evidence of general agreement across commentators on the need for new forms of learning to tackle global challenges" (p. 40). The challenge then becomes combining *hard skills* (scientific content) with *soft skills* (effective verbal written communication, career readiness, emotional I.Q., collaboration, creativity, work ethic) to build greater connections between the two. Within the context of STEM, essential skills include rigorous core content (biology, chemistry, Earth sciences, engineering, mathematics, physics, and technology) combined with critical thinking skills [20]. Curriculum that focuses on cognition of core constructs within the framework of 21CS provides opportunities for students to apply critical thinking and problem-solving in perspective with real-world scenarios.

Specific 21CS connections with STEM education include:

