We present SynFlo, a tangible museum exhibit for exploring bio-design. SynFlo utilizes active and concrete tangible tokens to allow visitors to experience a playful biodesign activity through complex interactivity with digital biological creations. We developed two versions of SynFlo: one that combines active tokens with real concrete objects bware) and one that consists of only abstract active tokens. Results from an evaluation in a museum indicate that both systems support learning. We discuss design choices for biology education tools to overcome confounders of biology and facilitate positive engagement and learning. Author Keywords Tangibles; active tokens; museum; children; bio-design; ACM Classification Keywords H.5.m. Information interfaces and presentation: User Interfaces---input devices and strategies, interaction styles.