Istraživanje konceptualnog razumijevanja atomskih spektara kod studenata

This dissertation describes an investigation on conceptual understanding of discrete line spectra that was conducted among more than 1000 science majors at a Croatian and at an American university. Some serious conceptual and reasoning difficulties were indentified. Students often could not relate spectral lines to transitions between atomic energy levels, nor did many recognize the experimental conditions necessary for the observation of line spectra. Results from the research guided the design and assessment of curriculum. The tutorial that was developed to help students understand the relationship between energy levels and atomic spectra proved effective. Significant progress was also made on research-based instructional materials related to the experimental apparatus. The investigation of student conceptual understanding was complemented by supplementary research that focused on the properties of plasma that are related to atomic processes. A determination of the parameters of mercury-indium plasma, which involved the application of experimental atomic spectroscopy methods, was an outcome of the experiments.Spektroskopija ima ključnu ulogu u modernoj fizici. Kroz povijest je opažanje diskretnih spektara dovelo do razvoja ideje o kvantizaciji energijskih nivoa u atomu i doprinijelo razvoju kvantne fizike. Danas se osnovni pojmovi vezani uz spektre uče već u srednjoj školi, kao i na uvodnim i specijaliziranim kolegijima iz fizike na fakultetima. Elektromagnetski spektri i priroda svjetlosti smatraju se najčešće poučavanom i najbitnijom temom na kolegijima iz osnova astronomije i astrofizike. Ovaj rad izvještava o istraživanju studentskog razumijevanja atomskih spektara. Istraživanje je provedeno na dva sveučilišta: na Prirodoslovno-matematičkom fakultetu Sveučilišta u Zagrebu i na University of Washington, Seattle, USA. Cilj istraživanja bio je provjeriti koliko dobro studenti nakon klasičnih predavanja razviju funkcionalno razumijevanje spektara. U istraživanjeu je sudjelovalo više od 1000 studenata. Na sveučilištu u Zagrebu populacija je uključivala studente druge i četvrte godine studija fizike. Na University of Washington populacija je uključivala studente na trećem dijelu uvodnog kolegija iz fizike. Jedan manji dio tih studenata bio je uključen u poseban „honors“ dio kolegija iz fizike, namijenjen najboljim studentima. Uz identifikaciju i analizu specifičnih studentskih poteškoća, ovaj rad opisuje i proces razvoja, primjene i evaluacije nastavnih materijala i strategija koje mogu pomoći u razrješavanju uočenih studentskih poteškoća. Studentske su poteškoće podijeljene u dvije velike grupe, koje se djelomično preklapaju: (A) poteškoće u povezivanju disketnih spektara, energijskih nivoa i prijelaza (B) poteškoće u razumijevanju uloge pojedinih dijelova eksperimentalnog postava u opažanju spektara. Istraživanje studentskog razumijevanja atomskih spektara upotpunjeno je dodatnim laboratorijskim istraživanjem visokotlačnog izboja žive i indija. Taj dio rada daje primjer primjene klasičnih spektroskopskih metoda u istraživanju parametara visokotlačnog izboja – temperature, gustoće neutralnih čestica u plazmi i tlaka. Parametri visokotlačnog izboja žive i indija određeni su istraživanjem oblika i širine spektralnih linija žive u vidljivom i bliskom infracrvenom dijelu spektra. Istraživanje studentskog razumijevanja atomskih spektara zahtijeva dublje razumijevanje atomskih procesa odgovornih za nastanak atomskih spektara, kao i praktično iskustvo u radu s eksperimentalnim postavom za emisijsku spektroskopiju. Teorijski okvir i eksperimentalne metode laboratorijskog dijela istraživanja učvrstili su bazu za pitanja razvijena u svrhu istraživanja studentskog razumijevanja spektara. Elektromagnetski spektar u nastavi se uobičajeno uvodi na uvodnim kolegijima fizike nakon što su studenti obradili teme iz fizikalne optike. Studenti tada trebaju proći put od razumijevanjavjetlosti kao elektromagnetskog vala do razvoja konceptualnog modela u kojem se svjetlost sastoji od fotona s diskretnim vrijednostima energije. Tijekom nastave studenti obično prvo vide demonstracijski pokus pri kojem bijela svjetlost upada na prizmu ili optičku rešetku, te kao rezultat daje kontinuirani spektar bijele svjetlosti na zastoru. Studentima se također prikaže i diskretni spektar žive ili vodika. Uvođenjem Balmerove, Lymanove i Pashenove serije studentima se objašnjava kako nastaje linijski spektar vodika. Uvodi se ideja da atomi u izvoru svjetlosti imaju samo diskretne, kvantizirane energijske nivoe i da je emitirana svjetlost rezultat prijelaza elektrona između dvaju energijskih nivoa. Svaki atom sadrži svoj jedinstveni skup energijskih nivoa, koji rezultira njegovim karakterističnim emisijskim spektrom. Tijekom uvođenja pojma spektra, nastavnici pretpostavljaju da su studenti upoznati s konceptima potrebnim za daljnje razumijevanje spektara i da ih razumiju. To uključuje: (1) svjetlost ima valna svojstva i svaka boja svjetlosti ima svoju specifičnu valnu duljinu i frekvenciju (2) svjetlost se prolazeći kroz prizmu lomi pod različitim kutovima, ovisno o valnoj duljini, a ako prolazi kroz optičku rešetku dolazi do interferencije svjetlosti (3) svjetlost se sastoji od fotona, gdje svaki foton sadrži energiju Ef= hc/λ (4) linijski spektar nastaje emisijom fotona pri prijelazu elektrona s jednog energijskog nivoa na drugi (ΔE = E2 – E1, gdje je ΔE = Ef

Rasch model based analysis of the Force Concept Inventory

The Force Concept Inventory (FCI) is an important diagnostic instrument which is widely used in the field of physics education research. It is therefore very important to evaluate and monitor its functioning using different tools for statistical analysis. One of such tools is the stochastic Rasch model, which enables construction of linear measures for persons and items from raw test scores and which can provide important insight in the structure and functioning of the test (how item difficulties are distributed within the test, how well the items fit the model, and how well the items work together to define the underlying construct). The data for the Rasch analysis come from the large-scale research conducted in 2006-07, which investigated Croatian high school students’ conceptual understanding of mechanics on a representative sample of 1676 students (age 17–18 years). The instrument used in research was the FCI. The average FCI score for the whole sample was found to be (27.7±0.4)%, indicating that most of the students were still non-Newtonians at the end of high school, despite the fact that physics is a compulsory subject in Croatian schools. The large set of obtained data was analyzed with the Rasch measurement computer software WINSTEPS 3.66. Since the FCI is routinely used as pretest and post-test on two very different types of population (non-Newtonian and predominantly Newtonian), an additional predominantly Newtonian sample (N=141, average FCI score of 64.5%) of first year students enrolled in introductory physics course at University of Zagreb was also analyzed. The Rasch model based analysis suggests that the FCI has succeeded in defining a sufficiently unidimensional construct for each population. The analysis of fit of data to the model found no grossly misfitting items which would degrade measurement. Some items with larger misfit and items with significantly different difficulties in the two samples of students do require further examination. The analysis revealed some problems with item distribution in the FCI and suggested that the FCI may function differently in non-Newtonian and predominantly Newtonian population. Some possible improvements of the test are suggested

Comparison of university students’ understanding of graphs in different contexts

This study investigates university students’ understanding of graphs in three different domains: mathematics, physics (kinematics), and contexts other than physics. Eight sets of parallel mathematics, physics, and other context questions about graphs were developed. A test consisting of these eight sets of questions (24 questions in all) was administered to 385 first year students at University of Zagreb who were either prospective physics or mathematics teachers or prospective physicists or mathematicians. Rasch analysis of data was conducted and linear measures for item difficulties were obtained. Average difficulties of items in three domains (mathematics, physics, and other contexts) and over two concepts (graph slope, area under the graph) were computed and compared. Analysis suggests that the variation of average difficulty among the three domains is much smaller for the concept of graph slope than for the concept of area under the graph. Most of the slope items are very close in difficulty, suggesting that students who have developed sufficient understanding of graph slope in mathematics are generally able to transfer it almost equally successfully to other contexts. A large difference was found between the difficulty of the concept of area under the graph in physics and other contexts on one side and mathematics on the other side. Comparison of average difficulty of the three domains suggests that mathematics without context is the easiest domain for students. Adding either physics or other context to mathematical items generally seems to increase item difficulty. No significant difference was found between the average item difficulty in physics and contexts other than physics, suggesting that physics (kinematics) remains a difficult context for most students despite the received instruction on kinematics in high school

Investigating physics teaching and learning in a university setting

Most of the initiatives taken by the European Community and by other countries internationally in the field of science education focus on elementary and secondary levels of education, and relatively few reports have analysed the state of science education in higher education. However, research in science education, and in particular in physics education, has shown repeatedly that the way teachers teach in elementary and secondary school is strongly influenced by their own prior experience as university students. The education that future professionals, such as scientists, engineers and science teachers, receive at the university is worthy of study, because it allows us to investigate student learning relatively independently of developmental issues, and because of the more rigorous treatment of physics topics at the university level. For these reasons, it seems appropriate to identify, analyse and provide solutions to the problems of teaching and learning related to the university physics curriculum. In this symposium, we present examples of physics education research from different countries that is focused on physics topics

Re-Design des Frankfurter Unterrichtskonzepts im Rahmen von EPo-EKo

Viele Lernende besitzen auch nach der Sekundarstufe I kein angemessenes Verständnis der elektrischen Grundgrößen „Spannung“, „Stromstärke“ und „Widerstand“ sowie ihrer wechselseitigen Beziehung in einfachen Stromkreisen. In der Studie von Burde (2018) konnte gezeigt werden, dass das Frankfurter Unterrichtskonzept auf Basis des Elektronengasmodells zu einem deutlich besseren konzeptionellen Verständnis beiträgt. Im Sinne des für Design-Based-Research-Ansätze typischen zyklischen Vorgehens von Entwicklung, Erprobung und Evaluation wurde das ursprüngliche Unterrichtskonzept für die aktuell laufende binationale Studie „Elektrizitätslehre mit Potenzial und Kontexten“ (EPo-EKo) weiterentwickelt. Grundlage hierfür waren einerseits die schulpraktischen Erfahrungen der Lehrkräfte in der Studie von Burde (2018) und andererseits kognitionspsychologische Erkenntnisse der „Dual-Process Theory“, wonach Lernende trotz besseren Wissens oftmals in ein intuitives, aber falsches Denkschema zurückfallen, statt eine physikalisch gesehen korrekte Argumentation zu verfolgen. Um eine unkomplizierte Implementierung im Regelunterricht zu ermöglichen, wurde das überarbeitete Frankfurter Unterrichtskonzept inzwischen unter dem Titel „Eine Einführung in die Elektrizitätslehre mit Potenzial“ in Form eines kostenfreien Schulbuchs veröffentlicht

Re-Design des Frankfurter Unterrichtskonzepts im Rahmen von EPo-EKo

Viele Lernende besitzen auch nach der Sekundarstufe I kein angemessenes Verständnis der elektrischen Grundgrößen „Spannung“, „Stromstärke“ und „Widerstand“ sowie ihrer wechselseitigen Beziehung in einfachen Stromkreisen. In der Studie von Burde (2018) konnte gezeigt werden, dass das Frankfurter Unterrichtskonzept auf Basis des Elektronengasmodells zu einem deutlich besseren konzeptionellen Verständnis beiträgt. Im Sinne des für Design-Based-Research-Ansätze typischen zyklischen Vorgehens von Entwicklung, Erprobung und Evaluation wurde das ursprüngliche Unterrichtskonzept für die aktuell laufende binationale Studie „Elektrizitätslehre mit Potenzial und Kontexten“ (EPo-EKo) weiterentwickelt. Grundlage hierfür waren einerseits die schulpraktischen Erfahrungen der Lehrkräfte in der Studie von Burde (2018) und andererseits kognitionspsychologische Erkenntnisse der „Dual-Process Theory“, wonach Lernende trotz besseren Wissens oftmals in ein intuitives, aber falsches Denkschema zurückfallen, statt eine physikalisch gesehen korrekte Argumentation zu verfolgen. Um eine unkomplizierte Implementierung im Regelunterricht zu ermöglichen, wurde das überarbeitete Frankfurter Unterrichtskonzept inzwischen unter dem Titel „Eine Einführung in die Elektrizitätslehre mit Potenzial“ in Form eines kostenfreien Schulbuchs veröffentlicht