## Dilber, Karaman and Duzgun, 2009

This Turkish study examines the effects of an instructional program that focuses on changing students' understanding of projectile motion. The program is designed to identify and confront misconceptions directly in students aged 17 and 18.

#### Evidence-based suggestions

• The experimental group's success in achieving conceptual change can be attributed to their engagement in activities that facilitated the revision of their previous conceptual understanding.
• Encourage students to struggle with their misconceptions by reading and discussing a conceptual change text.
• Computer simulations provided opportunities to visualise concepts
• Reading text designed with conceptual change in mind, combined with computer simulations, facilitates the understanding of projectile motion.
• Physics teachers should be aware of their students’ prior conceptual knowledge and typical misconceptions.
• Teachers-in-training should be informed about the usage and importance of conceptual change activities so that they can learn to plan their classes using these activities.

#### Learners’ ideas

• Many students were unable to explain projectile motion when an object was released from a moving platform. Instead, their common misconception was that the object fall vertically.
• Some students hold the belief that the size of gravitational force alone determines the speed at which falls, overlooking the height of the drop and air resistance.
• Some students believe that Earth’s gravity gets weaker as you near the poles.
• Students did not understand the significance of air resistance, believing that objects fall at different rates in a vacuum.
• Some believe that the mass of an object determines how long it takes to reach the ground.
• Students were unclear about how the atmosphere affects falling objects, believing that a falling object would slow continuously in the atmosphere rather than accelerate to a terminal velocity.
• Some students did not understand that the weight of an object depends on its mass, thinking that it only depends on the mass of the planet it is on.

#### Further suggestions

• Conceptual change text is effective generally for groups of students, however, it will need to be implemented by discussion for some individuals, particularly those with reading and writing difficulties.

### Study Structure

#### Aims

• To investigate the effectiveness of conceptual change-based instruction and traditionally designed physics instruction on students' understanding of projectile motion concepts.

#### Evidence collection

A test instrument, the Projectile Motion Concepts Test (PMCT), was developed by the researchers for the study. It contained 22 multiple-choice questions; each question had one correct answer and four distracters.  All items in the test were conceptual, and no quantitative calculations were needed to answer questions.

Two groups of students completed the same PMCT before and after a four-week study period. During the study period, the control group received standard physics instruction while the experimental group was instructed using conceptual change activities described in the paper. Both groups then completed the PMCT again.

The results of the pre and post-tests were analysed via an independent t-test of the two groups. The measured change in understanding for the experimental groups was significantly greater than that of the control group.

#### Details of the sample

The sample consisted of 82 high school students (36 boys and 46 girls) from two classes of a physics course. One class formed the control group of 39 students while the other formed the experimental group of 43 students.