STEM Activities in Determining Stoichiometric Mole Ratios for Secondary-School Chemistry Teaching Patcharee Chonkaew, Boonnak Sukhummek,* ,† and Chatree Faikhamta ‡ † King Mongkut’s University of Technology Thonburi, Bangkok 10140, Thailand ‡ Kasetsart University, Bangkok 10900, Thailand * S Supporting Information ABSTRACT: This article provides teachers with a guideline on how to create a science, technology, engineering, and mathematics (STEM) hands-on environment and prepare a small lab kit for determining stoichiometric mole ratios of the reaction between hydrogen gas and oxygen gas for secondary-school students. This guideline will provide teachers with a low-cost, simple and rapid workstation allowing and encouraging small groups of students to gain hands-on experience. The small lab kit is developed based on the principle of green chemistry resulting in less chemical usage, less time consumption and less waste production. This article also provides related STEM activities to improve the engagements, aspirations and attitudes of students toward science and technology. These activities provide students with a chance to explore the stoichiometric mole ratio concepts and challenge them toward STEM. KEYWORDS: High School/Introductory Chemistry, Inorganic Chemistry, Interdisciplinary/Multidisciplinary, Hands-On Learning/Manipulatives, Problem Solving/Decision Making, Gases, Green Chemistry, Microscale Lab, Stoichiometry ■ INTRODUCTION Numerous studies show that students’ attitudes and aspirations toward science are developed during secondary school. Students who studied science during secondary school are more likely to continue their study by enrolling in science courses at a university. This may also lead the students to pursue a profession in science-related careers. 1-3 Secondary education is regarded as an important stage for developing students’ interest and confidence in and utilization of science. 4 Many studies have also confirmed that teachers are a crucial element in guaranteeing positive growth in student achieve- ment. 5-7 Teachers can promote students by providing various different teaching and learning approaches or activities in order to inspire and encourage them. 8 A meaningful learning experience should offer a welcoming environment, encourage- ment, and collaboration. 9 This allows students to strengthen their knowledge on the basis of prior knowledge and new discoveries. One of the main aspects promoting the relevance and utility of science to students is authentic and real-life situations. 10 This creates opportunities for students to establish hypotheses, make decisions; solve problems; and perform complex, meaningful, and challenging tasks. Ordinarily, students are given some leading questions to answer. The students will then be given an assignment that requires the students to use the knowledge gained to present to the class. 9 Chemistry is a fundamental science subject and is commonly described as a difficult subject by students. This is mainly because chemistry is a study of invisible and untouchable things. 11,12 Chemistry requires an ability to link four levels of understanding: macroscopic, microscopic, symbolic, and process. 13,14 In the school chemistry curriculum, the concept of stoichiometry is fundamental to understanding other related concepts, such as solution, kinetics, acids and bases, and chemical equilibrium. Many students, including first-year undergraduate students, have difficulties in understanding and solving related stoichiometric problems, 15 especially when a reaction has more than one reactant. The students must determine the stoichiometric mole ratios related to all substances in the reaction. The stoichiometric mole ratio is very important in chemical calculations (e.g., calculations of theoretical yield, percent yield, and the quantities of mass and energy involved in the chemical reaction). 16 In order to gain a deep conceptual understanding in chemistry, students should be provided with situations where lessons taught in the classroom are adaptable to or implemented with real-world situations. 17 To solve any daily life problem, a single concept or principle is not sufficient. 18 For science, technology, engineering, and mathematics (STEM), integration of different concepts and principles is normally involved to solve authentic problems. Students are exposed to different kinds of teaching methods to increase their learning skills, that is, questioning, experimenting, and cooperating. 19 However, STEM in Received: November 30, 2018 Revised: April 1, 2019 Activity pubs.acs.org/jchemeduc Cite This: J. Chem. Educ. XXXX, XXX, XXX-XXX © XXXX American Chemical Society and Division of Chemical Education, Inc. A DOI: 10.1021/acs.jchemed.8b00985 J. Chem. Educ. XXXX, XXX, XXX-XXX J. Chem. Educ. Downloaded from pubs.acs.org by UNIV OF SUSSEX on 04/30/19. For personal use only.