Based on the work of Lev Vygotsky and Reuven Feirstein, the ZPD assessment identifies the learning outcomes that a student can achieve when given appropriate support[1]. This is a different approach to baseline assessment which identifies what a student appears to know or not know.

The ZPD is the gap between what the learner can do independently and what they can achieve with scaffolding, prompts and questioning. It is important that the learner is not given the answer, just hints and tips to help them to work the problem out for themselves. In the diagram below the ZPD is the area where learner can work with guidance[2].

Figure1

https://www.structural-learning.com/post/the-zone-of-proximal-development-a-teachers-guide

There are two types of approach to the ZPD:

1. A static approach, often used in assessment. The purpose is to identify learning potential. It involves testing what a student can achieve independently and then giving them scaffolding guidance with a re-test to see what progress has been made once appropriate help is provided.
2. The interactive or dynamic approach, often used to inform the teacher of the student’s next learning steps. The intention is to promote the development of learning by working within the ZPD and focusing on the interaction between the learner and teacher (or more knowledgeable peer).

At CandLE we use both approaches, through constant scaffolding in our teaching practice and learning support, and through measuring the difference between a student’s marks on tests for independent, scaffolded and modelled achievement.

Reasonable Adjustments

When we carry out an assessment of any kind, we first ensure that reasonable adjustments are put in place. Reasonable adjustments for students who rely on AAC have been agreed with GCSE exam boards to include[3]:

• Extra time. This is as much as is needed. We have known up to 800% extra time being offered but exam boards are now moving towards alternative assessment when this level of extra time is needed.
• Alternative Evidence Assessment (AEA). This involves the student tackling exam style questions that fulfill the assessment criteria for the exam across the range of learning within the subject over a period tackling one question at a time. This avoids fatigue whilst still enabling the students to demonstrate their understanding of the content of the course of study.
• Electronic Readers. These can be used even in the English assessments that are assessing understanding of text.
• Word prediction. This can be used in all subjects but will have a small implication on marks as those for spelling would be lost.
• Sentence starters. These should not have any reference to the learning content. The idea is to minimize time requirements and fatigue by offering obvious fillers and starters.
• Word-Banks. These can be used provided they do not provide leading information that would be connected to specific questions. A word bank should be generic and cover the whole subject although there have been instances of module word banks also accepted.
• A range of relevant quotes can be provided on working memory support grounds, but like word banks, they should not relate to specific questions and should be generic to the whole text.
• Allowing assessments to stretch over several days.
• Rest breaks as required.
• The use of a second screen. This can be very useful for several step questions or for having information you need to consult on one screen whilst you answer on a different screen.

Reasonable adjustments need to be put in place before a student is assessed and should form part of their ‘normal way of working’ in lessons as well as during assessments.

The ZPD Assessment Process

Students will be given an assessment linked or mapped to a particular age or stage, e.g. a Year 3 maths test. This assessment may be adapted into AAC software to make questions accessible. Then we carry out each of the following steps (see figure 1): 

1. The student attempts to answer the question on the assessment independently.
2. If the student struggles with all aspects of the question and is unable to produce even a partial answer, then scaffolding is used. Scaffolds are temporary supports that help a student achieve something that they cannot do alone. The support is gradually withdrawn as the student internalizes the skill or concept. Scaffolds might include:
   1. worked examples (not the question itself).
   2. Verbal prompts to think about the order something went in, for example a science experiment.
   3. breaking tasks down into manageable tasks e.g. breaking a question up into parts.
   4. Asking questions that support the student to think a little deeper.

Start with minimal help (a cue or a question), then move on to step by step prompts to help the organize their approach. At no point should scaffolding involve giving the correct answer or completing the steps for the student.

After providing some scaffolding, if the student can then answer the question, then this will be recorded as being answered correctly with scaffolding.

3. If the student is still unable to answer the question with scaffolding support, then provide modelling. This context means showing learners how to think through and respond to a question. The student still should not be provided with the answer but with the steps and guidance on how to get to the answer.

If the student can answer the question correctly after this enhanced modeling, then this will be recorded as such.

4. If the student after modelling is unable to reach the answer themselves, repeat the modelling and provide the answer and then asking the student to repeat it back to you (enhanced modelling).

5. If after scaffolding and modelling, the student is still unable to answer the question, this will be recorded as the student being unable to answer the question. Continue with the next question (you may want to explain or show the student what the correct answer is).

Figure 2: The Steps involved in a ZPD Assessment

Identifying the Zone of Proximal Development (ZPD)

The ZPD is where the student needs to be learning because potential is more likely to be realized when a student is making progress with support. Learning is most effective in a student’s Zone of Proximal Development (ZPD) because it targets skills that are just beyond their current ability but achievable with guidance—maximizing growth without overwhelming them. It is important in both learning and assessment, particularly for students who rely on AAC. Tasks in the ZPD are neither too easy nor too hard. This keeps students engaged and motivated. Working in the ZPD stretches a student’s thinking and problem-solving abilities, leading to deeper understanding. This cohort of students tend to have their learning potential underestimated because their current skills and understanding are often lower than what it could or should be had they had access to appropriate reasonable adjustments, the opportunity to catch up on missed learning and access to adaptive and differentiated pedagogical approaches.

Predictions made at year 7 assessments, for example, are less likely to give a reliable indication of potential GCSE results for a student who relies on AAC than it will for a non-disabled student. Using the ZPD creates a more equitable approach by measuring the student’s true potential.

The ZPD assessment also takes into consideration students’ gaps in knowledge, allowing them to demonstrate skills and understanding they may have at a higher level whilst helping educators identify gaps in learning that may lie ‘lower down’; this is represented in figure 2.

Figure 3: A Visual representation of where a student’s gaps in knowledge and understanding may be.

Marking System for Assessments

CandLE uses a marking system that provides marks for independent answering, answering with scaffolding, and answering after modelling. This enables us to ‘pin down’ the exact area where the student needs support to further their learning and develop skill and concept understanding. It helps us to ascertain if the student’s achievements on the assessment fall within the ZPD (e.g. is the assessment too easy, too hard or just right (within their ZPD)?).

The decision about the ZPD is arrived at by the following formula[4]:

• < 35% correct independently or with scaffolding or modelling = content is above the zone of proximal development (too hard)
• 36–69% correct independently or with scaffolding or modelling= content is in the zone of proximal development (just right!)
• > 70% correct independently or with scaffolding or modelling = content is below the zone of proximal development (too easy)

The form we use to record answers is below:

Carrying out assessments on an annual basis (or even more frequently) enables educators to develop a graph of learning development over time which can be compared with the curve of a graph made on independent achievements alone to compensate for factors impeding the demonstration of potential.

Using ZPD in the day-to-day learning process

Using the Zone of Proximal Development (ZPD) in all learning is essential because it ensures that teaching meets each learner where they are — not below or beyond their current capability. By identifying what a student can achieve with appropriate support, educators can design instruction that stretches thinking without causing frustration. Working within the ZPD allows teachers to scaffold learning through modelling, prompting, and collaboration, so students actively construct new understanding rather than passively receive information. Over time, as scaffolds are gradually withdrawn, learners internalise strategies and gain independence. In this way, the ZPD isn’t just a theory — it’s a practical tool for personalised, evidence-based teaching that promotes continual growth for every learner.

Incorporating the ZPD into learning resources

At CandLE we support the learning of students who rely on AAC by repurposing the software that supports communication to ensure that they have independent access to all the resources they need for learning including:

The input phase of learning. This includes all text, PowerPoint presentations, whiteboard overheads or any other information that the student needs to learn.

The elaboration phase of learning. This involves activities to practice newly learnt skills, consolidate concepts, and apply understanding to new contexts so that knowledge becomes flexible, transferable, and deeply embedded.

The output phase of learning. This is the assessment phase where the student demonstrates their understanding of concepts and skill development through performance, explanation, or application tasks. It provides evidence of mastery, highlights remaining gaps, and informs the next cycle of teaching and feedback.

Examples of ways in which we have achieved this within the software that students who rely on AAC can access.

In this example the help page has multiple choices. It is also designed for visual acuity:

In this example the student is given a means to count out loud:

The following shows reasonable adjustments being applied in GCSE English Literature with sentence starters, and a word bank:

Reasonable adjustments, scaffolding, finding the ZPD, differentiating learning resources and adaptive teaching all contribute to the optimisation of working memory which is essential for students to reach their learning potential. For students who rely on AAC accessibility is also key. They need to be provided with the most time efficient, least physically demanding and most independent way possible to support their learning.

[1] Kozulin, A. (2002). “Sociocultural theory and mediated learning experience.” School Psychology International, 23(1), 7–35.
doi:10.1177/0143034302023001733

[2] Vygotsky, L. S. (1978). Mind in Society: The Development of Higher Psychological Processes. Cambridge, MA: Harvard University Press.

[3] https://www.communicationmatters.org.uk/wp-content/uploads/2023/11/AAC-Exams-Access-Guidance-2023-2024.pdf

[4] https://www.nwea.org/blog/2025/the-zone-of-proximal-development-zpd-the-power-of-just-right/