A deficit based model from a quick Google search could be defined as:
"The deficit model of teaching, in which the teacher provides the learning to make good a deficit, stands in direct contrast to the belief that the teacher's role is to draw out learners' tacit knowledge and understanding through questioning and facilitation." Oxford Reference, 2020.
It's a model that has been prevalent in teaching from inception. We teach, we tell kids what they can't do. It's in contrast to a model where the focus is for the teacher to assist students understand the required information, develop a skill to complete a task or how to assimilate a concept within their existing conceptual framework and where it is not understood, diagnose and work with them to rectify the ommission.
When working with teachers with disgruntled parents, I am most interested in how well a teacher knows the student. If they know their friendship group, can tell where they sit in the class, can describe their demeanour, provide an accurate guide of their recent performance, talk about the positives of the child, it's a fair indicator that the student may not be telling the full story to their parents. In these cases the solutions required tend to be quite simple, are behaviour management related and easily remedied.
If a teacher is unaware of these things and can only describe what the student is not doing, it rings immediate alarm bells that this situation may need further investigation. These tend to be the cases of high ability or at least capable, underperforming students where a disconnection has occurred between the teacher, family and student (my specific area of interest). It can also be an indication that the teacher has defaulted to a deficit model and needs assistance to reconnect with their student.
In these cases it is important to let the air out of the situation, let everyone be heard and then gently guide the conversation back to what can be done to assist the student find success. It is not sufficient to say they are underperforming and set a goal of, "student will improve their grade by 10% by Term 3" unless it also says how they should achieve the goal. Goals set should be guided by the teacher with measures that are likely to reach an achievable outcome together with an aspirational goal. These measures should observable; processes, techniques, habits or revision that will be checked that they have been done and then measured for success against the goal.
If the student does what the teacher indicates and does not achieve success, they will lose confidence in the ability of the teacher. It is very important that whatever measure is set, that the probability of success is high. Often the measures initially set by a teacher are not specific, not measureable and have no way to ensure that the student is doing it correctly. In these cases they are very likely to fail with blame deflected to the student.
A recent case I was working on:
Problem: The student was writing a persuasive text rather than the required informational text.
Deficit Feedback to student: Student is not specific when stating her solution. Language used is not appropriate.
Alternate Response: Understanding of an informational text requires additional attention. Revisit an informational text with the student and contrast it with a persuasive text. Student to construct an informational text as a formative assessment, to be discussed and annotated with the teacher.
Problem: Level of detail is insufficient in written response.
Deficit Feedback to student: Response is full of waffle and preparation is insufficient.
Alternate response: Student would benefit from further developing her mind mapping techniques. Student to construct a mind map for next task and compare her response with a student that is highly capable in this skill. Student to submit next mind map created before constructing next written article. Student to construct a glossary of terms before next essay and review with teacher before next task.
and so on.. It is a different way of thinking and requires the responsibility of teaching to be firmly with the teacher working with the parent and student. With a reflective, timid, hardworking student in particular, asking them to self reflect and inform the teacher what they need to do is an intimidating, frightening and pointless task only likely to raise anxiety and lower performance further. This may in some cases remove the student from the care of the teacher (thus allowing the teacher to focus on other things) but is not in line with department policy on high care, high expectations.