Grade Eight Heather MacLean Algebra Grade Eight Heather MacLean

Algebraic Expression An algebraic expression is a shorthand way to write a sentence about a mathematical situation. A variable is used to represent an unknown number. Formulas are examples of algebraic expressions

General Curriculum Outcomes By the end of grade nine students will: Explore and explain, using physical models, the connections between arithmetic and algebraic operations. Apply operations to algebraic expressions to represent and solve relevant problems.

Specific Curriculum Outcomes Add and subtract algebraic terms concretely, pictorially, and symbolically to solve simple algebraic problems. Explore addition and subtraction of polynomial expression, concretely and pictorially

Which of the following expression match the variables A number doubled Seven more than a number Ten less than two times a number One-third of a number 1/3 r 4g t - 10 7 + n v2 x + 7 2k - 10 b3

Problems to try - #1 A rectangular flower garden as a length of 2b and a width of 3c. Create a diagram of the flower garden and write an expression of the perimeter of the flower garden.

Problem #2 Janice earns $9.00 an hour as a life guard. Write and expression for the amount of money she earns in a week. How much did she earn if she worked 10 hours last week?

Remember When adding algebraic expressions, you add the coefficients in front of variable and not the variable itself. Also, numbers without variable you add them as you always have. Example: 3x + 2 + 4x - 1 = 7x +1

Answers to Matching A number doubled = v2 Seven more than a number = 7 + n Ten less than two times a number = 2k - 10 One-third of a number = 1/3 r For purposes of placing a value on questions such as this one. I would suggest placing one point for each matching. This would mean the question has a value of four points. Also, when making matching questions it is important to remember to give more choice than only the correct number of answers. In this matching, there were four algebraic statements and eight algebraic expression to chose from.

Answer to Problem #1 2b 3c Perimeter of flower garden: P = length + width + length + width P = 2b + 3c + 2b + 3c P = 4b + 6c For the purposes of marking this question, I would use a marking scale. The question would be made out of 5 points. 5 points for correct diagram and solution to problem, including the definition of what perimeter is. 3 points for either correct diagram or correct solution to problem. 1 point for signs of attempting the problem. 0 points no attempt made.

Answer to problem #2 Let h be the number of hours, and M be the money Janice earns. M = $8.00h If h = 10 then, M = $8.00h M = $8 (10) M = $80 Janice made $80.00 if she worked 10 hours last week. When marking this question, I would separate the two question into three points each for a total of six points for the question. Part (a) for the algebraic expression: 3 points for explaining variable and correct equation. 2 points for defining one variable and correct equation or defining both variables and wrong equation. 1 point for correct equation, with no explanation. 0 points no attempt made Part (b) for how much money made: 3 points for filling in the proper value, correct answer and making a final statement. 2 points for two of the three above. Also, if they had the wrong equation in part a but the correct work for b. 1 point for one of the three. 0 points no attempt made.

More information If you want more on algebra check out: my home page: http://www.stfx.ca/people/x98/x98art/mywelcome.ca Other sites: http://forum.swarthmore.edu/algebra/alg.units.html; http://www.quickmath.com/www02/pages/modules/algebra/expand/basic/index.shtml

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