This paper describes the second in a series of studies exploring the acceptance of the subatomic structure of matter by 12-year-olds. The studies focus on a novel learning unit introducing an atomic model from electrons down to quarks, which is aimed to be used at an early stage in the physics curriculum. Three features are fundamental to the unit's design: conveying the central role of models in physics, focusing on linguistic accuracy, and the use of novel typographic illustrations. An initial study saw the iterative redesign and retesting of the unit through 20 one-on-one interviews with grade-6 students. Findings indicated broad acceptance of most of the unit's key ideas, hinting that the unit's final version is plausible for 12-year-olds. Subsequently, the research was focused on the perspective of teachers to gain insight into their evaluation of the unit's adequacy and didactic feasibility. Therefore, the current follow-up study was designed to introduce the proposed unit to grade-6 students. This time, instead of education researchers, 13 teachers conducted a set of 17 one-on-one interviews. The teachers had been introduced to the learning unit and the research method during a professional development programme. Our analysis showed that the unit's key ideas were broadly accepted by all the students, who adequately used them for problem-solving during the one-on-one interviews. Overall, the documented results validate our findings from the initial study and indicate that the learning unit is adequate and well-suited for a broad evaluation in the classroom.