This study examined how expert and novice (preservice) teachers solved mathematical modelling tasks as well as how they noticed written artifacts of student thinking that were in response to the mathematical modelling tasks. Some teachers in both groups were aware of the openness and underdetermination of the modelling tasks and that these characteristics implied that underlying assumptions needed to be made in order to solve the tasks. Indeed, nearly all of the expert teachers addressed the need to make assumptions for the Seashell Task. When examining student work, both expert and preservice teachers interpreted positive aspects in the students’ solutions and provided feedback to students. However, almost all of the expert teachers responded by asking questions, whereas around a third of preservice teachers directly corrected students’ mistakes and another third pointed out mistakes without correcting them. This study provides a new angle to study teachers’ mathematical competencies, the assessment of modelling competencies, and considerations for the development of teachers’ modelling competencies.

本研究考察了专家和新手（职前）教师如何解决数学建模任务，以及他们如何注意到学生对数学建模任务的书面思考。两组中的一些教师都意识到建模任务的开放性和不确定性，并且这些特征意味着需要做出基本假设才能解决任务。事实上，几乎所有的专家教师都谈到了为贝壳任务做出假设的必要性。在检查学生作业时，专家和职前教师都解释了学生解决方案中的积极方面，并向学生提供了反馈。然而，几乎所有的专家老师都通过提问来回答，而大约三分之一的职前教师直接纠正学生的错误，另有三分之一的教师指出错误而不纠正。本研究为教师数学能力研究、建模能力评估、教师建模能力发展思考提供了新的视角。