CONCEPTUAL DIFFICULTIES IN PLANT NUTRITION: EPISTEMOLOGICAL ANALYSIS OF THE TOPIC AND A SYSTEMATIC REVIEW OF LITERATURE
The teaching and learning of the scientific model of plant nutrition, despite being a pivotal topic of the science curricula of most countries, is one of the most troublesome issues in science education. Indeed, although its correct understanding is often described as a prerequisite to understand ecosystem functioning and several of the current socioscientific issues (e.g. climate change, sustainable food production…), research in science education has revealed that students from multiple countries and educational levels present scientifically inaccurate ideas and teaching and learning difficulties regarding plant nutrition. Therefore, the purpose of the present study is twofold.
On the one hand, we perform an epistemological analysis of the topic in order to identify the key conceptual ideas that every student should articulate in order to construct and fully grasp the scientific model of plant nutrition by the end of compulsory education. Thus, based on the historical development of plant nutrition knowledge, the difficulties the scientific community had to overcome and the arguments used to build the nowadays consensual scientific model, four epistemological keys are defined:
1) plants’ nutrition, unlike animals’, is autotrophic although they absorb certain substances from the environment;
2) the fundamental chemical reaction in plant nutrition is photosynthesis;
3) the way in which plants obtain energy is via respiration; and
4) plant nutrition is an essential process for the functioning of ecosystems since it plays the role of primary production and oxygen supply.
On the other hand, we conduct a systematic review of literature on plant nutrition teaching and learning research with the objective of identifying and characterising the articles of the last two decades [2000-2021] that have studied students’ conceptions and difficulties on the topic either with diagnostic purposes or before and after a didactic intervention. The unit of analysis is composed of scientific articles indexed in Web of Science (WOS), Scopus and ERIC and the systematic review follows the recommendations of PRISMA. Hence, from the initial search that identified 2593 records, 87 articles that fulfil the abovementioned inclusion criteria are included in the review and analysed regarding the objective, research instruments, country, educational level sampled and epistemological ideas taken into consideration. Preliminary results disclose that 56.3% of the research conducted regarding difficulties is aimed to merely identify and describe students’ conceptual understanding, and of those that deal with how students’ conceptions change before and after a specific intervention (43.7%), only the 36.8% present a quasi-experimental or experimental research design. Besides, it is also worth noting that, of all the studies examined, just the 36.8% consider and assess the four key ideas earlier defined. Therefore, the results evidence the need of moving on from diagnostic assessments of well-documented students’ conceptions towards the systematic design, implementation and evaluation of evidence-informed teaching-learning sequences in order to improve students’ conceptual understanding of plant nutrition and achieve a scientifically literate and empowered citizenship.