IB MYP 2 Mathematics || Criterion B || Expression through Algebraic Sequences

IB MYP 2 Mathematics

Criterion B Task – Expression: Algebraic Sequences

Instructions

• You have 50 minutes to complete this task.
• Show all your working and explain your thinking using correct mathematical language, symbols, and steps.
• Use full sentences when describing patterns, rules, and formulas.

Task: Algebraic Sequences

1. Part A – Recognizing Patterns:
   The following sequences are given. Determine the rule for the \(n^{th}\) term in words and in algebraic form:
   • Sequence 1: 3, 7, 11, 15, …
   • Sequence 2: 2, 6, 18, 54, …
   • Sequence 3: 5, 9, 14, 20, …
2. Part B – Finding Terms:
   Using your rules from Part A, find the following:
   • The 10th term of Sequence 1
   • The 5th term of Sequence 2
   • The 8th term of Sequence 3
3. Part C – Explaining Your Reasoning:
   For each sequence, explain:
   • How you determined the type of sequence (arithmetic or geometric)
   • How you derived the algebraic expression for the \(n^{th}\) term
   • How you used the expression to calculate specific terms
4. Part D – Create Your Own Sequence:
   Write your own arithmetic or geometric sequence with at least 5 terms. Then:
   • Describe the rule in words
   • Write the algebraic formula for the \(n^{th}\) term
   • Find the 6th term using your formula

Criterion B Rubric – Expression

Level	Description
0	The student does not reach a standard described by any of the descriptors below.
1–2	Communicates mathematical ideas with limited clarity. Little use of correct notation or reasoning.
3–4	Communicates mathematical ideas with some clarity. Some correct use of notation and reasoning.
5–6	Mathematical ideas are clearly expressed. Procedures and reasoning are mostly correct and logical.
7–8	Mathematical ideas are communicated effectively and coherently. Procedures are correct and reasoning is logical and detailed, with consistent use of proper notation.