There are the only two studies available on the types of solutions--unsaturated, saturated, supersaturated, dilute and concentrate--in the related literature with respect to students' understanding. But, no study focuses on remediation of students' alternative conceptions with regard to the aforementioned concepts, based on the assumption that learners actively construct and transform their own meanings, rather than passively acquire and accumulate knowledge transmitted to them. Therefore, this study can fill in a gap in the literature by designing an activity on the types of solutions in regard to four-step constructivist teaching strategy. Also, some suggestions were made for future studies and further investigation.