Te reo Māori terms
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Learning objective overview
Master Teaching Guide coverage for this objective.
NA4-7
NZC26-P4-ALG-ER-P-Y9-04NZC26-P3-ALG-ER-K-Y7-01NZC26-P3-ALG-ER-K-Y7-06
Resources
- CorbettMaths on forming expressionsQuestions PDF · Answers
- Beta: Skills in Chapters 8, pg 152-156
- Beta: Ex 7.02, pgs 136 – 137
Terminology
- variable
- expression
- equation
- term
- coefficient
- constant
- operation
- irrational number
Task goals
- Use a letter to represent an unknown quantity, and explain what that variable stands for in a real-world context.
- Translate a word sentence into an algebraic expression, using brackets or a fraction bar to show the intended order of operations, e.g. "3 more than two sevenths of a number" becomes $\dfrac{2}{7}x+3$.
- Form an expression for a total cost, age, or measurement from a described situation, e.g. a $\$5$ base charge plus $\$3$ per kilometre $k$.
- Form and simplify an expression for the perimeter or area of a shape whose side lengths are given as variables.
- Form an expression that includes a fraction, a percentage increase, or an irrational number such as $\pi$.
- Distinguish an expression from an equation, and explain why an expression cannot be "solved" the way an equation can.
Where this fits
What leads into this objective, and where it goes next.
Before
Substitution
You are here
Forming expressions
A variable can be used to represent: an unknown number, often in formulae (e.g. s in s^2); a quantity that can vary or change (e.g. y = 3x + 4; A = bh); a specific unknown value to be solved (e.g. 3a = 18).
Statement▸
Algebra has its own specialised notation to express relationships and operations concisely, including: 3b in place of b + b + b, 3 × b, and b × 3; b in place of 1b; ab in place of a × b or b × a (in alphabetical order); a^2 in place of a × a, a^3 in place of a × a × a; a/b in place of a ÷ b and a × 1/b; a in place of a^1; 1 in place of a/a when a ≠ 0.
Statement▸
Also under NA4-7:
For teachers
Need the fuller teaching notes for this objective? Open the Teacher guidance PDF.