Algebra - Substitution - Presentation

In the algebra-focused lesson on substitution, students delve into the process of replacing variables with numerical values within algebraic expressions. The lesson starts by prompting students to consider what substitution means and where they might have encountered it before. The first activity involves simple substitution tasks, where students are given values for variables such as 'a' and 'b', and then asked to calculate the sum of these variables. For example, if 'a' equals 5 and 'b' equals 7, students would substitute these values into the expression 'a + b + b' to find the result, which in this case is 19. This activity reinforces the concept that substitution is simply the replacement of letters with numbers to evaluate an expression.

As the lesson progresses, students are presented with more complex substitution scenarios, including expressions with multiple variables and different operations like addition and subtraction. In one activity, students substitute given values for 'm', 'x', and 'c' into various expressions, calculating the results, such as '-1', '9.5', and '8'. Another activity introduces the challenge of substituting fractions into expressions, which adds an additional layer of complexity and prompts students to consider how fractions impact algebraic calculations. For example, substituting 'm' as 25 and 't' as 1/2 into the expression 'mt' results in 12.5. The lesson also includes reasoning tasks where students must apply their substitution skills to solve equations and correct misconceptions, further solidifying their understanding of the substitution process in algebra.