Choose any nonnegative number. x 15 (x) 2 152 (square) Square your number. = x 2 = 225 x 2 ∙ 9 225 9 (multiply) Multiply the result by 9. = 9x 2 = 2025 (square root) Take the square root of the result. = 3x = 45 3x + 15 45 + 15 (add) Add 15 to the result. = 3x + 15 = 60 60 ÷ 3 (divide) Divide the result by 3. = x + 5 = 20 x + 5 – 5 20 – 5 (subtract) Subtract 5. = x = 15 It’s your original number! x (Yeah!) 15 (Yeah!) Excellent Acceptable Unacceptable You have correctly shown Your trick has a few minor Your trick has major errors. why your trick works errors. (using variables). Your trick gives the desired Your trick works for only Your trick works for only Correctness result for any number you tell some numbers in your some numbers or no of Trick your audience they can domain (or you didn’t “warn” numbers in your domain (or (10 points) choose. (i.e., the domain is your audience). you didn’t “warn” your correct) audience). (8 – 10 points) (4 – 7 points) (0 – 3 points) Your trick involves several You have several steps, but Your trick involves only a few steps that are complicated they aren’t complicated steps, and they aren’t enough that your audience enough to trick an audience. complicated enough to trick would be surprised. an audience. Complexity You used four or more You used only three different You used two or fewer of Trick different operations. operations. different operations. (6 points) Your trick is quite different Your trick is somewhat Your trick is very similar to from the example given. similar to the example given. the example given. (5 – 6 points) (3 – 4 points) (0 – 2 points) Each step of the example is There are a few minor errors There are major errors in Correctness done correctly. in your example. your example. of Example (3 – 4 points) (2 points) (0 – 1 point) (4 points) Don’t steal this one—make yours different! Operation Step General Example
Choose any nonnegative number. x 15 (square) Square your number. (x) 2 = x 2 152 = 225 (multiply) Multiply the result by 9. x 2 ∙ 9 = 9x 2 225 9 = 2025 (square root) Take the square root of the result. = 3x = 45 (add) Add 15 to the result. 3x + 15 = 3x + 15 45 + 15 = 60 (divide) Divide the result by 3. = x + 5 60 ÷ 3 = 20 (subtract) Subtract 5. x + 5 – 5 = x 20 – 5 = 15 It’s your original number! x (Yeah!) 15 (Yeah!) Excellent Acceptable Unacceptable Correctness of Trick (10 points) You have correctly shown why your trick works (using variables). Your trick has a few minor errors. Your trick has major errors. Your trick gives the desired result for any number you tell your audience they can choose. (i.e., the domain is correct) Your trick works for only some numbers in your domain (or you didn’t “warn” your audience). Your trick works for only some numbers or no numbers in your domain (or you didn’t “warn” your audience). (8 – 10 points) (4 – 7 points) (0 – 3 points) Complexity of Trick (6 points) Your trick involves several steps that are complicated enough that your audience would be surprised. You have several steps, but they aren’t complicated enough to trick an audience. Your trick involves only a few steps, and they aren’t complicated enough to trick an audience. You used four or more different operations. You used only three different operations. You used two or fewer different operations. Your trick is quite different from the example given. Your trick is somewhat similar to the example given. Your trick is very similar to the example given. (5 – 6 points) (3 – 4 points) (0 – 2 points) Correctness of Example (4 points) Each step of the example is done correctly. There are a few minor errors in your example. There are major errors in your example. (3 – 4 points) (2 points) (0 – 1 point) Don’t steal this one—make yours different! Operation Step General Example