The Ontario achievement chart, and how to weight it

Four categories, one mark, and no Ministry instruction about the percentages. Here is what the chart actually says, and what that leaves to you.

Written by a practising Ontario teacher · Last reviewed: September 2026

The four categories

Every Ontario curriculum document contains an achievement chart with the same four categories. The wording is adapted per subject; the structure never changes.

Knowledge and Understanding

What the student knows, and whether they grasp what it means. Recall plus comprehension — the difference between naming the stages of mitosis and explaining why the order matters.

Thinking

The use of critical and creative processes: planning, inquiry, analysis, evaluation. This is the category that most often goes unassessed, because it is the hardest to write a question for.

Communication

Conveying meaning, for an audience, in an appropriate form. Not "neatness", and not a second spelling mark — whether the thinking reached the reader.

Application

Transfer: using the knowledge in a context that is not the one it was taught in. If the task looks exactly like the lesson, it is probably assessing Knowledge.

How to weight them

This is the question every new Ontario teacher asks, and the honest answer is that the Ministry does not set the percentages. The achievement chart states that the categories are interrelated and that all four must be assessed; curriculum documents signal emphasis by subject; the split is a professional decision made at the school, department or teacher level.

Equal weighting — 25% each — is the most common default, and it is defensible precisely because it makes no claim. What matters more than the numbers is that whatever you choose is consistent, communicated, and actually reflected in the tasks you set. A 25% Thinking weight means nothing if none of your assessments ask students to think.

The check worth running

Take your weighting, then count what you have actually assessed in each category this term. If Thinking is 25% of the mark and 6% of the evidence, the weighting is describing an intention rather than a result.

Putting it in a gradebook

Categories only do work if every assessment is filed into one. That sounds like admin, and it is, right up until the moment you need to tell a parent which kind of difficulty their child is having — at which point a single overall percentage cannot answer the question and four category averages can.

It also changes what a report card comment can say. "Struggling in science" is a sentence anyone could write. "Strong Knowledge, but Application drops whenever the context is unfamiliar" is a sentence only the gradebook knows, and it is the one that tells a family what to do next.

Frequently asked questions

Does the Ministry require 25% per category?

No. The achievement chart requires that all four categories be assessed and treated as interrelated. It does not prescribe percentage weights; those are a professional decision, often set at the department or school level.

What does KATC stand for?

Knowledge, Application, Thinking, Communication — staffroom shorthand for the four achievement chart categories. The Ministry does not use the acronym, and you will see the letters in different orders.

Should late work lose marks?

Growing Success separates achievement from learning skills. Lateness is a work habit and is reported under Responsibility; deducting from the achievement mark makes the mark describe something other than what the student can do. Boards vary in how strictly this is applied.

Can one assessment cover more than one category?

Yes, and most rich tasks do. A lab report can carry Knowledge, Thinking and Communication marks separately. What matters is that each category’s mark is derived from evidence that actually addresses it.

Ontario assessment guide — the rest of the series
Report card comments from category averages

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