CTS Guide: Gravitational Force, pp 180-181- Section IV Research Summaries
Concept of Gravitational Force
Elementary school students typically do not understand gravity as a force. If students do view weight as a force, they often think it is the air that exerts this downward force (AAAS 2009).
Gravity and Atmosphere
Some students believe that gravity only extends as far as Earth’s atmosphere (Williamson and Willoughby 2012).
Relating gravity to air provides insight into students’ ideas about gravity being something that resides outside of objects rather than all objects exerting gravitational pull. Some students describe a “holding” idea that an atmosphere holds gravity in (Driver et al. 1994).
Ruggiero et al. (1985) interviewed 22 Italian middle school students ages 12–13 about astronomy. Although none of the questions explicitly mentioned air, several students indicated that air is needed for gravity to function: “Weight exists only on the Earth, because there is air ... and gets smaller higher up because air is rarefied” (pp. 187–188). When asked to describe the motion of objects on the Moon, some students said that objects there floated because of the absence of gravity. Some students believed that the lack of air on the Moon meant that there was no gravity there. Others viewed gravity as something that is both Earth-centered and Earth-specific. The Moon was considered to be too far from the Earth to experience gravity.
Gravity as a Force Throughout the Universe
In Stead and Osborne’s (1980) study of 258 middle school students, 44% said there was no gravity on the Moon. The idea that not all planets have gravity was common among these students. Over 75% said there is no gravity in space. The researchers suggested that the science- fiction idea of “weightlessness” contributed to this misconception.