Einstein's elevator in class: A self-construction by students for the study of the equivalence principle

According to the principle of equivalence, it is impossible to distinguish between gravity and inertial forces that a noninertial observer experiences in his own frame of reference. For example, let's consider an elevator in space that is being accelerated in one direction. An observer inside it would feel as if there was gravity force pulling him toward the opposite direction. The same holds for a person in a stationary elevator located in Earth's gravitational field. No experiment enables us to distinguish between the accelerating elevator in space and the motionless elevator near Earth's surface. Strictly speaking, when the gravitational field is non-uniform (like Earth's), the equivalence principle holds only for experiments in elevators that are small enough and that take place over a short enough period of time (Fig. 1). However, performing an experiment in an elevator in space is impractical. On the other hand, it is easy to combine both forces on the same observer, i.e., gravity and a fictitious inertial force due to acceleration. Imagine an observer in an elevator that falls freely within Earth's gravitational field. The observer experiences gravity pulling him down while it might be said that the inertial force due to gravity acceleration g pulls him up. Gravity and inertial force cancel each other, (mis)leading the observer to believe there is no gravitational field. This study outlines our implementation of a self-construction idea that we have found useful in teaching introductory physics students (undergraduate, non-majors). © 2016 American Association of Physics Teachers

Yield and quality of lettuce and rocket grown in floating culture system

In recent years, there has been a growing trend towards cultivating leafy vegetables in hydroponic systems. Floating system is an alternative hydroponic system suitable for the production of baby vegetable products, ready-to eat salads and minimally processed leafy vegetables. However, the implementation of this system for the production of fully grown leafy vegetables is not sufficiently studied. The aim of the present study was to examine the potential of floating system as an alternative growing technique of lettuce and rocket plants, as well as the effect of nitrogen (N) application rate (three treatments 100, 150 and 200 mg L-1 of N) on plant physiology, quality and yield during three growing periods. The results showed that increasing the N application rate resulted in an increase of fresh weight of the aerial parts of both lettuce and rocket, while total yield ranged between 12.0 to 41.9 and 8.0 to 30.2 kg m-2 of fresh leaves, for lettuce and rocket, respectively. In addition, increasing the nitrogen rate resulted in higher number of leaves for lettuce and rocket, as well as in a significant increase in the rate of photosynthesis. A similar increase was observed in nitrate, K, Mg and Mn content in the leaves, without however exceeding the permissible limits for nitrates in any case. In conclusion, the use of floating raft technique for lettuce and rocket cultivation in order to produce not only seedlings production or baby products, but also fully grown plants of high quality is highly recommended

A Lab of Hands-on STEM Experiments for Primary Teachers at CERN

In this paper, we present school science teaching and learning activities using large research infrastructures as tools for primary teachers eager to engage their students in cutting-edge physics and engineering research. The activities were deployed from 2016 to 2019 in the framework of a professional development course addressed to primary school teachers, which took place at CERN. We focus on a laboratory of electromagnetism which Greek teachers tested with their students after participating in the course. The Large Hadron Collider and the particle detectors at CERN served as exciting engineering paradigms. The laboratory introduced participants to learning-by-doing methodologies for conducting simple experiments that aimed to foster student learning. The proposed laboratory is examined in terms of its impact on both teachers' and students' knowledge regarding experiments and the construction of engineering models as well as on their basic understanding of scientific and engineering research

Greek MOOC of Experiments with Simple Materials for Students Generates Significant Findings for Teachers and Physics Education

In October 2019, the first Greek Massive Open Online Course on science experiments for students took place online and lasted five weeks. Its content consisted of a substantial number of science experiments based on the school curriculum with simple, everyday materials. The audience addressed were not only students but also science teachers and people interested in science. A total of 7266 enrollments were recorded, the vast majority of participants being teachers of primary and secondary education. The data received during the course and the statistics that followed revealed notable findings on the need for epistemological development among teachers teaching science and engineering, the extent of teaching through experiments in Greek schools, the gender-biased inequalities in the communities of students and teachers, and the challenges that exist in the field. The course was repeated in March 2020 as soon as the pandemic spread in the country

A Step that Paves the Way of Teaching Modern Electrical Circuits

Conventional incandescent bulbs are widely used in science education experiments. Today incandescent bulbs are being replaced by LED bulbs, which students encounter quite often in their daily lives, but they ignore how LEDs operate in a simple circuit. Also, the electronic devices used every day are getting smaller and smaller in scale, preventing students from understanding that they simply incorporate basic elements of electrical circuits that they learn in school. This research seeks to find ways to make this integration and to evaluate learning outcomes in primary school students