1.3 Written-Response Communication and Rubrics

How the written-response marks are built

The Math 30-2 diploma has two written-response questions. According to the bulletin, each question consists of four parts and is scored out of 7 marks: one 1-mark part followed by three 2-mark parts. The questions address multiple cognitive levels, so you should expect a mix of straightforward calculation, interpretation, comparison, modeling, and explanation. A written-response page is not a place to hide thinking; it is the place to display it efficiently.

The general scoring guide evaluates four broad kinds of evidence: understanding the problem or mathematical concept, correctly applying knowledge and skills, using problem-solving strategies while explaining solutions and procedures, and communicating mathematical ideas. The specific scoring guide for an exam question translates those expectations into point-by-point criteria. That is why two students can have the same final number but different scores: one may show a complete, contextual, well-labeled solution, while the other may write a number with no evidence of how it was obtained.

A full-credit response pattern

Use the pattern claim, evidence, calculation, conclusion. The claim tells the marker what you are doing. The evidence identifies the function, graph feature, table value, restriction, or formula. The calculation shows the mathematical path. The conclusion answers the question in the original words, with units and appropriate rounding.

Worked example: A population of bacteria in a lab is modeled by P = 120(1.18)^t, where t is the number of hours after noon and P is the population. A written-response part asks: Compare the meaning of the numerical values 120 and 1.18 in this model.

A weak response says, The answer is 120 and 1.18. That copies numbers but does not compare their meanings. A partial response says, 120 is the start and 1.18 is growth. That shows some understanding but lacks context and comparison. A stronger response says, The value 120 represents the modeled bacteria population at noon, when t = 0. The value 1.18 means the population is multiplied by 1.18 each hour, so the hourly growth rate is 18 percent. The two values describe different features of the model: 120 is the initial amount, while 1.18 describes how the amount changes over time.

Notice that the stronger response does not add unnecessary length. It names both parameters, connects them to the context, states the growth rate, and compares their roles. That is the type of communication Math 30-2 written response is designed to assess.

How partial marks should change your behaviour

The official written-response information emphasizes that attempts may be worth partial marks and that each part is scored separately. This should change how you write under pressure. If part b is difficult, do not abandon part c automatically; later parts may use a value from earlier work or may ask for interpretation that you can still address. If your graphing calculator gives a model but you are unsure about one coefficient, write what you know accurately and label it. Valid partial evidence is better than silence.

For a 2-mark part, a response may receive partial credit for a correct strategy with incomplete execution, or for describing one relevant parameter correctly when the part asks for a comparison of two. A near-complete response can lose value if it fails to express the answer in the requested way, such as an actual calendar year instead of years after a starting point, or a time of day instead of hours after midnight. The marker can only score what appears in the response.

Communication checklist

• Define variables when the problem context is complex.
• State restrictions or non-permissible values before solving rational expressions or equations.
• Keep enough calculator evidence to show what model, window, intersection, regression, or substitution was used.
• Round at the requested final stage and include units when the quantity has units.
• Answer the directing word: a calculation does not replace a justification, and a sketch does not replace an interpretation.

Diploma traps

One common trap is treating a command word as decoration. If the question says justify, the marker is looking for supporting evidence, not just a final claim. If it says interpret, a bare coordinate such as (6, 420) is not enough; the response should say what 6 and 420 mean in the situation. If it says compare, both objects must appear in the answer. Another trap is writing a calculator command without a mathematical conclusion. Technology can support the solution, but it does not communicate the solution by itself.

Finally, make written-response work easy to mark. Number the parts, align equations, label graphs, and box or underline final answers only after the reasoning is complete. The goal is not beautiful handwriting; the goal is unambiguous evidence of Math 30-2 thinking.