A worksheet related to subject of physical and chemical changes were developed in this study. In the process of development, the activity was implemented with 94 students from Primary Science Education Department at Karadeniz Technical University Fatih Education Faculty in the General Laboratory-II. This activity constitutes of four phase. The first phase begins with a focus question that the students are firstly to explain with causes individually. At the second phase, they are to prepare solutions at required concentration and volume. The third phase asks the students to follow the directions in the experiment and then they are to note their observation on the worksheets. The fourth phase constitutes of assessment part of the activity included three questions related to events at the operation steps. Then, the students are asked to reflect what they have learned by giving them choices to explain these events at the fifth phase. (C) 2010 Elsevier Ltd. All rights reserved.