Comparing the Impact of Two Science-as-Inquiry Methods on the NOS Understanding of High-School Biology Students

Abstract

The current study compared the effectiveness of two methods in biology teaching that are based on the science-as-inquiry approach: visits to authentic university laboratories (AULs) and analyzing adapted primary literature (APL). The methods’ effectiveness was measured in terms of high-school students’ increased understanding following a 6-week intervention that emphasized five major aspects of the nature of science (NOS): the tentativeness of scientific understanding, the cooperative nature of the scientific process, methodological diversity, the sociocultural embeddedness of scientific knowledge, and the aims of scientific inquiry. A quasi-experimental, pre-post control design was applied, utilizing quantitative evaluation methods. Findings indicate that teaching NOS in biology high-school classes using science-as-inquiry methods is an effective approach for enhancing NOS understanding. Both of the proposed methods appear to be promising; however, the AUL method was found to be more effective for enabling advanced-level high-school biology students’ understanding of these NOS aspects. In conclusion, both AUL and APL are potentially effective methods that can be adapted for teaching various biology subjects in different cultural contexts.

Appendix 1. Abstracts of the adapted articles (translated from Hebrew to English)

Original article: Recent shrinkage of the range of the Eastern Spadefoot Toad, Pelobates syriacus (Amphibia: Anura): archeological evidence from the Bronze Age in Israel

Delfino Masimo, Guy Bar-Oz, & Lior Weissbrod

Published in Zoology in the Middle East, 40, 45–52 (2007)

Abstract for students: Shrinkage of the geographic distribution of the Eastern Spadefoot Toad: archeological evidence from the Bronze Age in Israel

Following Masimo, Bar-Oz, and Weissbrod, 2007.

Archeological evidence can serve to increase our understanding of the past distribution of species that have become extinct, and it sheds light on recent changes in species variability. Such evidence constitutes complex research findings, due to its uniqueness and the fact that it cannot be replicated. Comparing the distribution of current species with that of their precursor species is needed in order to accurately assess the influence and the repercussions that climate change and human activity had on the environment, and it can help us understand the population structure of current species.

This study can be considered as an example of “basic science,” because it elucidates changes in species distribution; it can also be considered an example of “applied science,” because it reveals the ways in which human activity affected environmental conditions, which in turn can lead to the development of strategies for environmental preservation. Amphibians are particularly useful for conducting such a comparison, because they are considered reliable indicators of environmental conditions both on land and in water. Hence, they provide a particularly useful way to describe what local conditions were like in a specific era, as they reflect slow-paced developmental changes that occurred over many generations. Furthermore, the particular resources for which many amphibian species rely on their environment are well known, and it is assumed that their ancient precursors had the similar needs.

This article presents findings (fossils) retrieved from the archeological site, evidence of amphibian life in different eras. The analysis of the remains collected in the Ara Burial Cave in Lower Galilee, Israel (Late Bronze Age II, c. 1300–1200 BCE), permitted the identification of 725 remains of various species of Spadefoot Toad. Despite the relative rarity of such remains (attributable to a single individual), their presence in the Ara cave testifies to a wider range of the taxon in the recent past, given that in the present, this species cannot be found in the cave. Additional evidence of the species wider dispersion in the past was found also in several Israeli Late Pleistocene archeological sites All of this evidence suggests recent environmental changes, which may be due to climatic fluctuations as well as to human impact. An accurate analysis of the shrinkage of the geographic distribution of the Eastern Spadefoot Toad and of the environmental changes that led to this shrinkage will assist in the preparation of conservation or reintroduction plans in Israel.

Conclusion: Comparing the distribution of fossils with the current species distribution can serve to gain insight into the changes in environmental conditions that occurred over time and to understand the role that human activity had in causing these changes.

Original article: Effects of eight growth factors on the differentiation of cells derived from human embryonic stem cells

Maya Schuldiner, Ofra Yanuka, Joseph Itskovitz-Eldor, Douglas A. Melton, and Nissim Benvenisty

Published in PNAS, 97, 11,307–11,312 (2000).

Abstract for students: effects of eight growth factors on the differentiation of cells derived from human embryonic stem cells

Following Schuldiner, Yanuka, Itskovitz-Eldor, Melton, and Benvenisty, 2000.

The process of embryo development begins with a single fertilized cell. Embryonic development occurs as cells divide; thus, the number of cells increases, and tissue and organs form through cell differentiation. Embryonic stem cells are harvested from embryos in very early stages of development and then are placed in a cell culture, where they can grow in vitro, that is, outside of the living organism, in the laboratory, under carefully monitored conditions.

Stem cells are characterized by two major traits:

• 1. The ability to constantly self-multiply in a cell culture

• 2. The ability to differentiate (become a mature cell with a specific role and thus different from the parent cell) into every type of cell in the human body, for example, blood cells, muscle cells, nerve cells, etc.

Cell differentiation leads to changes in cell morphology (structure) and function. In the differentiation process, specific genes are expressed that are characteristic of specific cell types, for example, genes of white blood cells or genes of antibodies.

When embryonic stem cells are grown in a cell culture under specific conditions (appropriate temperature and salinity, among other factors), cell clusters are formed, which after a few days become small droplet-shaped bodies that are called embryoid bodies. To use stem cells for purposes of basic science or applied science (for example, for medical research), scientists need to develop techniques by which to direct cell differentiation towards a particular function. One of the ways to try to accomplish this is by growing the cells in a solution that contains special proteins that influence the development and growth of the cells. These proteins are called growth factors, and different growth factors naturally induce cell differentiation into different types of cells.

This article describes a study that aimed to review the distinct effects of eight different growth factors on stem cell differentiation, to determine whether it is possible to control the cell differentiation and thus direct stem cells to differentiate into specific cell types.

The findings show that human embryonic stem cells that developed from embryoid bodies expressed a receptor for each of these growth factors, and that their different effects were evident by differentiation into cells with different morphologies. However, none of the growth factors directed differentiation exclusively to one cell type. By analyzing the resulting cell morphology, we were able to detect three categories of morphological differences associated with three groups of growth factors. This analysis is an initial step towards demonstrating that it is possible to use specific factors to direct the differentiation of human embryonic stem cells in vitro.

1.1 Appendix 2

Table 6 Examples of students’ quotes