The objectives of this research were 1) to compare physical science learning achievement in the learning unit entitled “Food” of the experimental group between pretest and posttest and 2) to compare physical science learning achievement in the learning unit entitled “Food” between the experimental and the control groups of posttest. The samples were 77 students, 40 students (experimental group) and 37 students (control group), of the grade 10th students from Songphinongwitthaya School, Suphanburi province, of the first semester in 2022, by cluster sampling. The research tools consisted of 1) lesson plans using the flipped classroom 2) lesson plans using the conventional approach and 3) a 30-item multiple choice learning achievement test of the physical science subject in the learning unit entitled “Food” with an Index of Concordance (IOC) between .67 and 1.00. The difficulty value ranged between .57 and .83 while the power of discrimination ranged between .20 and .47 and the confidence value was .56. The descriptive statistical analysis and t-test were used in analyze the data. The research results revealed that the experimental group had mean score of posttest on physical science learning achievement in the learning unit entitled “Food” higher than before the experiment and higher than the control group at .05 level of significance.