Abstract:

There are many misconceptions about science topics that develop in childhood and often persist into adulthood, one is that heaviest objects fall quickly than the lighter ones, another is that the air does not have any weight, and another is that in absence of air there are not gravity. Children need appropriate explanations in order to make sense the world around them; both gravity and air are important concepts because they are ubiquitous. This study presents the results of a science workshop whose main target is build prior understanding about gravity with Galileo´s experiments, where he demonstrated that the speed of falling bodies, with different weight but the same shape, is the same. The workshop consists of eight experiments: three of them were conceived by Galileo to discover the acceleration of gravity, and five experiments are about air properties. Also it is included a questionnaire (with seven questions that can be answer with the experiments) that the students has to answer before and after completing the experiments. We provide the instructions, and a manual to carry on the workshop, to more than 600 teachers of elementary schools in the state of Querétaro; many of them put this workshop to their 22,000 students of elementary schools in the state of Querétaro. A survey of the pre/post test data was used in order to evaluate the effectiveness in promote a change in the misconceptions mentioned above; we use the Hake indicator (g) that is “a rough measure of the average effectiveness of a course in promoting conceptual understanding”. The value of (g) is the ratio of the actual average gain to the maximum possible gain, thus, the maximum value is 1. In the analysis we used the data from 65 groups, that range from 4° to 6° grade, with a total number of students N= 2260, from San Juan del Río and Querétaro, the two main cities of the state of Queretaro, México. Here, we present only the results of two multiple choices questions: 1) What body falls first? a) The most lightweight, b) the heaviest, c) equal (the correct answer is c); 2) How heavy is the air? a) Nothing, b) half the water, c) a thousand times less than water (c is the correct answer). For the first question, 56 groups achieved an average gain (g)=0.53 and near 50 % of the groups obtains more than (g)= 0.7; nevertheless 24.5 % obtained a (g)<= 0. For the second question, 65 groups achieved (g)=0.61, near 55 % of the groups obtained more than (g)= 0.7, and only 9 % have no gain at all. These results suggest that the classroom use of this workshop, could build better notions of these science topics in the childhood. The workshop is available on line at: http://www.geociencias.unam.mx/geociencias/experimentos/taller_ciencia.html.

Keywords:

Gravity, science education, experimental learning, misconceptions.