This Self Learning Material (SLM) is based on the existing Secondary Level Science Curriculum and textbook of Grade 10. This material is prepared for open school students. It is is a support or reference materials to the existing secondary textbook and it has been prepared keeping the principles of open/distance learning in view. It contains varieties of activities in simple language and it is believed to be student friendly and comprehensive. It is prepared by a team of experts comprising subject experts, curriculum specialists and experienced teachers.