The research aimed to describe pupils inter-dialogue during learning polyhedron. It based on learning obstacle. In didactical obstacles are found problems of conceptual interrelation, thinking continuity, and limitation experience of pupils in the polyhedron concept. So, the researchers designed a didactical design to minimize the learning obstacle by creating a more organizer and solve learning trajectory. The design implementation done on the pupils of grade VIII in Bandung during 3 continuous meetings. Inter-dialogue is expected to emerge when didactic design is designed so pupils dialogue with group friends to find solutions for solving problems. Dialogue that produces critical questions is commonly known as Socratic dialogue. The main idea in Socratic dialogue is the teacher’s task is not to give knowledge or provide information to pupils but the task of the teacher designing a learning situation where pupils will ask critical questions. The researcher using phenomenological studies to uncover pupils experience. By using Nonaka theory, the researcher found the pupils knowledge. The results showed the pupils intra-dialogue system in solving the polyhedron geometrical problem of phenomenological studies.

Vacuum residue (VR) is potential to be used as a feedstock for mesophase pitch (MP) production because of its low cost and aromatic content. MP, which is a liquid-crystalline state of VR, may be used as precursor of activated carbon (AC). Gum rosin containing conjugated double bonds may be added to and can improve crystallinity and pore surface area in further processes of carbonisation and activation. In the present study, co-pyrolysis was carried out in a stirred tank reactor at 450°C with holding time for 120 minutes. The amount of gum rosin mixed with VR was varied 0, 5, 10 and 15% wt of VR. The precursor products had C/H mole ratio of about 2.43, 2.37, 2.28, and 2.01 by increasing gum rosin added. Subsequently, this precursor underwent carbonization at 700°C with holding time for 120 minutes under N2 flow and activation. KOH solution was used as activating agent to the precursor of activated carbon. Activated carbon gave higher surface area and lower C/H atom ratio with increasing gum rosin added during co-pyrolysis. With gum rosin addition, surface areas of ACs were 120.81, 194.56, 312.36, dan 462.19 m2/g, respectively, and crystallite sizes increased from 8 to 22 Å.