B7.2.2 · Strand 2, sub-strand 2

Algebraic Expressions

Using letters for numbers, simplifying, expanding and substituting into expressions.

1. Lesson 1 · B7.2.2.1.1 · about 45 min

   Writing Algebraic Expressions from Words

   Market women, trotro mates and shopkeepers do algebra every day without calling it algebra: "Whatever the price of one tuber, three tubers cost three times that." In this lesson you will learn to turn word instructions like these into short algebraic expressions, using letters to stand for numbers we do not know yet.

2. Lesson 2 · B7.2.2.1.2 · about 45 min

   Adding and Subtracting Algebraic Expressions

   A long expression such as $3x + 2y + 2x + y$ is like a market basket with yams and bags of gari thrown in anyhow. In this lesson you will learn to sort it out — collect the like terms together, add or subtract their coefficients (whole numbers, fractions or decimals) and write the answer in its simplest form. You will also use this to write the perimeter of shapes.

3. Lesson 3 · B7.2.2.1.3 · about 45 min

   Multiplying and Dividing Algebraic Expressions

   Carpenters, tilers and farmers multiply lengths to find areas, and divide to share land or materials equally. In this lesson you will multiply and divide algebraic terms — numbers with numbers, letters with letters — including negative and fraction coefficients, and use this to write the area of shapes.

4. Lesson 4 · B7.2.2.1.4 · about 45 min

   Substituting Values into Algebraic Expressions

   An expression such as $1.5u + 12$ is like a recipe that works for any number: put in the number of electricity units you used and out comes your bill. In this lesson you will replace letters by numbers — including negative numbers and fractions — and work out the value of expressions using the correct order of operations.

5. Lesson 5 · B7.2.2.1.5 · about 50 min

   Simplifying Expressions Using the Properties of Operations

   The commutative, associative and distributive properties are the rules that let us rearrange, regroup and remove brackets without changing the value of an expression. In this lesson you will use them to expand brackets such as $3(x + 2)$, simplify expressions that mix all four operations, and work confidently with fraction coefficients — skills you will need for solving equations and for the BECE.