Secondary Science - Gravity
From Eduwiki
Making Sense of Secondary Science: Research into Children’s Ideas
Driver et al, 1994
Summarized by Scott Holloway
Children’s Ideas About Physical Processes The Earth’s Gravity
Gravity A detailed study by Stead and Osborne of New Zealand pupils ages 11 to 17 found three main ideas about gravity: pushing, pulling or holding. Holding was the most common perception which was combined with the idea that air pressing down helps keep things from floating away. The idea that air and gravity are linked is common among students. Earth’s magnetism and spin are also believed to be connected to gravity by many students.
Most students correctly believe that gravity does change with height above the earth’s surface, but assume too great a change. Ruggiero et al found that one third of students believed that gravity increase with height above the earth’s surface.
Weight Students generally do not connect weight of an object to the force of gravity acting on the object. Some students believe objects can have weight without gravity (astronauts). Some students see weight as a property of an object and gravity as a property of space. Watts found that some secondary students believe that gravity does not act the same way all the time, even on the same object. Some students believe that an object in water has no gravity or less gravity acting on it so it weighs less and can float.
Falling Students do not always feel that objects need a force to cause them to fall. Vicentini-Missoni found students believed falling was caused by a loss in equilibrium not in response to gravity. Osborne found that students believe that heavier objects fall faster due to having a greater acceleration due to gravity. Some secondary students feel that gravity acts only when an object falls. Some students feel that objects contain a force that counter acts gravity and that allows them to go up. Some students feel that gravity creates a constant velocity during a fall and that greater gravity creates greater constant speed. Still other students felt that objects speed up because gravity gets stronger the closer an object gets to the ground.
