There is an urgent need to update the science curricula content in light of the Next Generation Science Standards (NGSS). The purpose of this research is to present a proposal of the science curricula content in light of the NGSS. Secondly, the effect of NGSS on conceptual understanding and higher-thinking skills among first-year intermediate students is also analyzed. This work is unique as no research is conducted on the topic as per the best of our knowledge. Hence, the research may motivate further studies on the topic. The semi-experimental method was used to know the impact of teaching science in conceptual understanding and higher thinking skills. The sample consisted of 62 students divided into two groups. The control group was led the “nature of material” unit in the first-year intermediate book, issued by the Ministry of Education in 1438 AH. A list of science tools was prepared for analyzing the content of science curricula in light of Next-Generation Science Standards (NGSS). Two tests were prepared, a conceptual understanding test and a higher thinking skills test. The research revealed different results: the availability degree of science for the next-generation science standards curricula in the intermediate stage was low. The developed unit’s size effect in light of these standards on conceptual understanding and higher-thinking skills among the research sample was high with a value of 0.89-0.91.