Gravity and Weight :
Misconceptions and Educational Research

Common misconceptions include:

Some research has been conducted on how students understand the Moon’s changing appearance and position in the sky, and on most effective ways to teach this subject:

Learning About the Earth’s Shape and Gravity: A Guide for Teachers and Curriculum Developers: Agan, L. and Sneider, C., 2004, The Astronomy Education Review, Volume 2, p. 90-117.
The scientific model of the Earth in space--consisting of the spherical Earth and gravity concepts--is one of the first models that children encounter in their science classes. Children’s understanding of these concepts is essential for further conceptual development in astronomy. This article provides a thorough review of educational research concerning children’s development of Earth shape and gravity concepts in the context of national standards and the history of science. Based on this review, the authors recommend instructional approaches at appropriate grade levels to enable students to fully grasp these fundamental concepts. 

The Ceres Project has excellent background information, a list of potential misconceptions, and an excellent activity to help teachers discover their own student’s preconceptions on gravity.