# 2.1 Constructing expressions

2.1 Constructing expressions
WALT:  use letters to represent numbers

use the correct order of operations in algebraic expressions
write and use expressions.

WILF: I can understand that the order of operations rules apply to algebra.
I can use these rules to write algebraic terms and expressions.
I can read an expression written in words and convert it to an expression written in algebraic terms, and vice versa.

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Slide 1: Slide
MathSecondary Education

This lesson contains 10 slides, with interactive quizzes and text slides.

Lesson duration is: 40 min

## Items in this lesson

2.1 Constructing expressions
WALT:  use letters to represent numbers

use the correct order of operations in algebraic expressions
write and use expressions.

WILF: I can understand that the order of operations rules apply to algebra.
I can use these rules to write algebraic terms and expressions.
I can read an expression written in words and convert it to an expression written in algebraic terms, and vice versa.

#### Slide 1 -Slide

2.1 Constructing expressions
In algebra you can use a letter to represent an unknown number

An expression contains numbers and letters, but not an equals sign.
An equation contains numbers and letters and an equals sign.
Example:
5n + 4 = 19 is an equation.
5n + 4 is an expression.

#### Slide 2 -Slide

Sort  the expressions and oequations.
Expressions
Equations
4x+9
-9ab
6(m+3)=10
4n=8
3/4a
5a+6b-4c
y=mx+b
P=2(l+w)

#### Slide 3 -Drag question

2.1 Constructing expressions
• coefficient - a number in front of a variable in an algebraic expression
• term - a single number or variable, or numbers and variables multiplied together
• constant - a number on its own (with no variable)
• variable - a symbol, usually a letter, that can represent any one of a set of values

#### Slide 4 -Slide

Label the parts of the expression.
-
Coefficients
terms
variables
constant

#### Slide 5 -Drag question

Words and Phrases to Math Symbols
Addition
Subtraction
Multiplication
Division
Equal
Plus
Increased By
Altogether
More Than
Total of
Take Away
Less
Less Than
Fewer Than
Difference
Triple
Increased By a Factor
Product
Of
Multiple
Quotient of
Divisor
Per
Ratio of
Split Up
is
was
the same as
Yields
Will be

#### Slide 6 -Drag question

Maliha thinks of a number, y.
Write an expression for the number Maliha gets when she:
multiplies the number by 2
divides the number by 2
multiplies the number by 4, then adds 3
multiplies the number by 2, then subtracts 5
multiplies the number by 2, then subtracts the result from 5
divides the number by 4, then adds 3
2y
4y + 3
2y − 5
5 − 2y

#### Slide 7 -Drag question

Write an expression for each of these.

1) x more than y
2) x less than y
3) m more than two times n

4) a less than three times b
5) p multiplied by q
6) four times g multiplied by h

#### Slide 8 -Open question

Write an expression for each of these
a) I think of a number x. I multiply the number by 6, then add 1.
b) I think of a number x. I multiply the number by 4, then subtract 9.
c) I think of a number x. I divide the number by 6, then subtract 1.
d) I think of a number x. I divide the number by 2, then add 7.
e) think of a number x. I multiply the number by 2, then subtract the result from 25.

#### Slide 9 -Open question

Write an expression for each of these situations. You can choose your own letters, but make sure that you explain what your letters represent.
a) the total cost of two tacos and four burritos
b) the total cost of eight lemon cakes and five carrot cakes
c) the total value of six gold coins is doubled
d) the total value of five silver coins is tripled