This paper proposes an inductive learning environment which supports learners' knowledge acquisition from trial and error in experiments. The environment aims to assist learners in finding causal rules of experiments together with its meta-process of findings. We introduced two principal functions of the support environment : the internal experiment and the bi-directional interface. The internal experimental module manipulates the learning environment in the same way as the learner does. It tries to derive the causal rules and verifies the correctness of hypotheses by experiments. The bi-directional interface provides both the learner and the system with a channel to access the learning environment on equal condition. Both of the learner and the system has the same right to manipulate and receives the same information from the learning environment. These two principal functions provide the system with an ability to acquire rules by experiment, to monitor learner's operations and to do cooperative work with the learner. We introduced strategy space of operation and hypothesis space, so that the internal experimental module may deduce correct rules by using these two sources of knowledge, and may infer learner's state of trials in discovery. Finally, we propose methods of assisting learners together with examples excerpted from a courseware about the proportional relation.