A few warm-ups have been used to prep for this skill, and it is simple plug-in and use the order of operations. Below is an example to illustrate how to use substitution.
Ex. -3x^2 +4 if x = -2
1) Plug in -2 everywhere that x exists. The -2 is traded in for the x and x is no longer in the expression. -3(-2)^2 + 4
2) Understand what substituting the value for the variable means: The coefficient for x means to multiply the variable (-2) by -3 since there are 3 groups of x. The exponent was directly beside the variable so the base for the exponent can only be -2. We have discussed the difference between (-3x)^2 and -3x^2 where the first example means to square everything within the parentheses to get 9x^2 and the second example only squares the variable and not the coefficient.
3) Use the order of operations to solve.
P - Nothing to do within the parentheses here. Also note the parentheses are optional and were added to show the number inside was negative to separate it from the rest of the problem.
E - The exponent can be worked since we have a value for x now so (-2)^2 is 4.
MD - From left to right, we have multiplication of -3*4 = -12.
AS - From left to right, we have addition of -12 + 4 = -8.
We used a silent stations activity to practice this skill.
Students completed a half sheet of paper (8 questions with 1 question already worked as an example) on evaluating expressions that should be stapled into this journal entry.