Early impairments in social attention prevent children with autism spectrum disorder (ASD) from acquiring social information and disrupt their social behavior development. We present Co-Space, a tangible system that supports children with ASD aged 4-8 years in developing social attention and social behaviors through collaborative and embodied play in a classroom setting. Children can paint tangible hemispheres, insert them on a projection board, and then press or rotate the hemispheres independently or collaboratively to view dynamic audiovisual feedback. We leveraged the strengths of children with ASD (e.g., who may have visual strengths and prefer repetitive actions) by providing them with tangible hemispheres to engage their participation. We utilized codependent design and dynamic audiovisual cues to facilitate children’s social attention and encourage their collaboration and potential social behaviors. We demonstrated multiple ways to integrate the tangible system into classroom activities. We discuss the benefits of designing tangible systems for supporting social attention and social behaviors for children with ASD through play in the classroom.