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3. Partnership 21st Century Skills (Framework for 21st Century Learning, 2006)
4. S. Chu, R. Reynold, M. Notari, N. Traveres, and C. Lee, “21st Century Skills Development through Inquiry Based Learning From Theory to Practice” (Springer Science, Singapure, 2017)
5. M. S. Brookhard, “How to Assess Higher-Order Thinking Skills in Your Classroom” (ASCD, Virginia USA: Alexandria, 2010)