AbstractAuthentic dialogue demands that we respond, interpret and sometimes disagree with others' ideas—a key component of participation in a democratic society. Yet the sharing and uptake of different ideas can be hampered by traditional online platforms which divide students into isolated threads. To tackle this issue, we introduce two novel online forums designed to foster engagement and idea exchange: a linear chat, akin to SMS, and a collaborative writing forum we call CREW. Seventy‐three graduate students, divided into 18 small groups, tested these forums. We used discourse analysis to measure idea uptake and other dialogic features. From this analysis, seven discussions emerged as particularly interactive and engaging, exhibiting a high uptake‐to‐turn ratio. We noticed linear chat encouraged a high proportion of uptake, but also produced ‘tangles’—breaks in related post chains. CREW discussions sparked similar engagement but resolved most tangles since they required a collaborative written response. This study offers fresh insights in both research and teaching for improving online discussions. Practitioner notesWhat is already known about this topic A vital practice for scholarly dialogue and democratic discourse is uptake: building on what others have written or said. Instead of encouraging uptake of others' words and ideas, typical online discussions in Learning Management Systems (LMSs) can inadvertently isolate students in separate threads. What this paper adds We introduce and analyse two new, innovative types of online discussions that may encourage more uptake of others' words and ideas. To eliminate isolation and encourage uptake, a linear chat forum makes all posts visible, but may produce interruptions, or ‘tangles’. A forum that includes collaborative responsive writing requires participants to converge on a collective response, encouraging dialogue and overcoming tangles. Implications for practice/policy Teachers and other stakeholders might consider how discussion forum designs in LMSs can support or limit authentic dialogue. Practitioners might consider how to incorporate deliberation about a shared focus into online discussions. Instructors might avoid tangles by aligning assignment purposes with dialogic principles: posing authentic questions that invite multiple interpretations and require uptake of others' responses.