Last modified: 2020-09-18
Abstract
The concept of fluid dynamics underlies several phenomenons and technologies that develop in everyday life. However, students still have a low understanding of concepts in fluid dynamics topic. The purpose of this study is to improve understanding and describe students' difficulties in the topic of fluid dynamics after the Inquiry-Based Learning integrated STEM with Formative Assessment (IBL-STEM with FA) learning process.
IBL places students as scientiest, who can think deductively or inductively with asking questions during learning. Several studies have shown that IBL can improve students' science process skills, learning achievement, self-efficacy, reasoning ability, experimental skills, and understanding of concepts. Some students are less interested in this learning because the laboratorium experiment experience is less synchronous with real life. However, some research on IBL suggests combining it with the STEM approach. The research showed that IBL-STEM was able to improve the understanding of concepts and scientific literacy in the topic of Newton's Law. However, the integration of STEM into learning requires time for students to get used to the complex phases. Therefore, a formative assessment on the tested IBL-STEM is needed to help students achieve learning objectives effectively. IBL-STEM with FA learning have a great opportunity to improve students' understanding of concepts.
The results showed that students' understanding of concepts increased significantly with the N-gain in medium category and the d-effect size in very large category. After the learning process, students still find it very difficult to understand (1) fluid volume flow rate remains constant, and (2) fluid pressure is directly proportional to the pipe cross-sectional area, but inversely proportional to flow velocity.
This study uses a mixed methods design with embedded experimental models. The research subjects in this study were 34 students of class XI in Jombang, who were selected by purposive sampling. This research uses The Fluid Dynamics Understanding Test instrument in the form of 12 reasoned multiple-choice questions with a reliability of 0.774. This test instrument includes 3 subtopics of fluid dynamic, namely the Continuity Equation, Bernoulli's Equattion, and the Application of Bernoulli's Equation; and 6 cognitive levels, namely Remember (C1), Understand (C2), Apply (C3), Analyze (C4), Evaluate (C5), and Create (C6). Data was collected through pretest, posttest and interview. Data analysis in this study used paired t-test, N-gain, d-effect, and a description of the reasons for students' answers.
Paired t-test yields a value of sig. (2-tailed)<0.05 so there is a difference between the pretest and posttest values during the treatment. These results indicate that there is an influence of the IBL-STEM with FA learning model on the understanding of students' fluid dynamics concepts. The increase of students’ concepts understanding after treatment is shown by the value of N-gain = 0.63 (medium category).
In the Continuity Equation subtopic, the N-gain for cognitive level indicators C2, C4, C5 and C6 are 0.89 (High), -0.73 (Low), 0.89 (High), and 0.58 (Medium), respectively. This shows that there is improvement in students’ understanding on the indicator of understanding the relationship between speed and radius of cross section in the continuity equation (C2), determining the value of fluid flow velocity in everyday life problems (C5), and constructing the application of the continuity equation in technical field (C6).
However, students still have a decreased understanding of indicators analyzing the concept of the Continuity Equation for the case of differences in flow velocity at the end of the pipe (C4). This result is reinforced by students' incorrect answer choices with the percentage of distractors of more than 20% which are shown in the following Table 1.
Table 1. Recap of Reasonings for Students' Answer on The Continuity Equation Subtopic
Cognitive Level
Item Indicators
Reason for Wrong Answer
Posttest Distractor (%)
C2
Presented a horizontal pipe scheme with different cross sections, students can explain the relationship of fluid velocity at two different points
Students assume the velocity of fluid flow is inversely proportional to the radius of the pipe
23.5
C4
Analyze the concept of the Continuity Equation for the case of differences in volume flow rate at the two pipe ends
Students assume that the decrease in speed is due to the reduction in the radius of the output pipe
21
Students assume the difference in diameter results in reduced speed
21
C6
Constructing the application of the continuity equation in the technical field
Students tend to choose the answer choices with the least amount of editorial
24
The effectiveness of the treatment of students' understanding of concepts before and after the treatment is shown by the value of d-effect size = 3.645 (very large category). This means that the IBL-STEM with FA learning implementation has an impact in the very large category specifically on the understanding increases among the students.
The results showed that students' conceptual understanding increased significantly with N-gain = 0.63 (medium category) and d-effect size = 3,645 (very large category). After the learning process students still find it very difficult to understand two things, namely (1) constant valuable fluid flow rate so that it does not depend on the radius or diameter of the pipe cross section, but can be reduced due to changes in the physical state of the pipe such as leakage; and (2) fluid pressure is directly proportional to the cross-sectional area of the pipe, but inversely proportional to the flow velocity. In addition, students still find it difficult to analyze (1) the velocity of fluid flow inversely proportional to the square of the cross-section radius, (2) construct the proof of fixed fluid flow rate, (3) lift force by two aircraft wings, and (4) phenomeana of someone is pulled towards the direction of a moving train near him, or (5) a reservoir of water can flow water in a faucet at a greater rate.