<![CDATA[Waste water from the process of making tofu causes environmental pollution because it has acidic and cloudy. The acidic nature of the tofu waste is a result of the process of adding vinegar to the clumping process. Therefore, it is necessary to treat waste before it is discharged into river bodies in order to reduce organic matter and suspended and dissolved solids in the waste water. One of the effective and low cost ways is the phytoremediation process. The water plant that can be used as a remediator is Pistia stratiotes. This study was to determine the interaction between variations weight and remained of Pistia stratiotes on the improvement of the quality tofu waste water and its use as a source of biology learning. The approach and type of this research are quantitative and true experiment. Sampling of waste water was carried out at the industrial center of making tofu as much as 70 liters in Pakunden Village, taking Pistia stratiotes from the swamps around the river flow of Kali Lahar, Blitar City. Sample testing was carried out at Jasa Tirta I, Malang. This study consisted of 10 treatment groups and 3 control groups with 3 repetitions with variations weight of 80 g, 90 g, 100 g, 110g, 120g and remained of 7 days and 14 days. The experimental design used in this experiment was a completely randomized design, the results of this study can be used as a source of information on Biology learning that has been adjusted to the 6 requirements of learning resources.]]>
