CTS Guide: Cell Division and Differentiation pp. 94-95- Section IV Research Summaries
Meaning of “Growth”
Flores, Tovar, and Gallegos (2003): Confusion about the differences between mitosis and meiosis, both functionally and in purpose, and where these two forms of cell division occur are common. This confusion may contribute to students failure to recognize that cell division contributes to growth.
Carey (1985): For preschool children, growth means getting bigger and results from intentional activities or a birthday. Around age 9 children develop a physiological concept of growth. Other studies also showed growth as synonymous with getting bigger or taller rather than cells dividing.
Shafer (1979): In a word association study starting with age 15 through adult, including biology teachers, the youngest students (around age 15) used measures of growth such as large, fat, narrow. Few of all ages mentioned the word weight in association with growth.
Cell Division and Cellular Basis for Growth
·Researchers noted that one of the difficulties students have in understanding cell division is what happens to the size of cells before and after division. Students need to understand that the cell enlarges before division in order to have two copies of about the same size as the original cell (Riemeier and Gropengiefser (2008).
Several studies have shown students’ difficulties in assimilating taught concepts of cell division, cell enlargement, and cell differentiation. One study showed that only 69% of respondents who were asked what accounts for growth realized that growth was occurring when a cell divides in two (Driver et al. 1994).
A study by Zamora and Guerra (1993) asked middle school students to describe what happens to cells as an organism grows. The most frequent response was that cells grow, referring to the increase in cell size, not cell number.
Smith (1991) reports that some students have difficulty understanding concepts related to cell division and genetics because they can’t distinguish between doubling, pairing, and separating as well as figuring out whether these processes occur in mitosis, meiosis, or both.
In a study by Hackling and Treagust (1984) less than half of 10th grade students understood that growth was the result of cell division.
Hackling and Treagust (1982): In a study of Australian 15-year-olds, there was poor understanding of the role of cell division in growth.
Okeke and Wood Robinson (1980): In a study of Nigerian students and their English counterparts, both groups showed confusion between cell division, cell enlargement, and cell differentiation. 20% of the group thought cells got smaller with every cell division.
Differentiation
Hackling and Treagust (1982): Secondary students thought the idea that an entire organism, with its variety of different types of cells, can be formed from one cell through numerous cell divisions, to be counterintuitive.