Problem Solving on the Wildlife Refuge
Super Value Kit
Materials Included In Kit
(for each student group)
Wildlife Puzzle Cards, set of 6
Wildlife Ratio Cards, set of 8
Additional Materials Required
Photocopy enough Problem Solving on the Wildlife Refuge Student Instructions handouts and the accompanying worksheets for each student.
- Distribute the student instructions and worksheets, Wildlife Puzzle Cards and Wildlife Ratio Cards to each student group.
- Go through the instructions and the sample problem with the students.
- Show students how the Wildlife Ratio Cards may be turned upside-down if needed in order to have the animal units placed correctly. Note: Just as with playing cards, the numerals will always be right-side up on the left side of each card even when the animal pictures are upside-down.
- Introduction to Unit Factoring. This kit contains enough reusable materials for 15 student groups: 15 sets each of the Wildlife Puzzle and Ratio Cards.
- This is a good activity to do early in the school year and may be revisited often as various types of problems are encountered in the curriculum.
- Enhance the experience by decorating the classroom with stuffed animals and playing appropriate music as the students enter or even by wearing a safari hat. Let your imagination be your guide.
- The Wildlife Puzzle Cards are designed to allow the instructor flexibility. All six puzzles do not need to be completed by each group. The Wildlife Puzzle Cards are numbered in order of degree of difficulty (puzzles 1 and 2 require two ratio cards, puzzles 3 and 4 require three, and puzzles 5 and 6 require four ratios cards). The odd-numbered puzzle cards have whole number solutions and the even-numbered puzzle cards have solutions that require rounding to the nearest whole number. Certain puzzles may be omitted depending on the ability of the students or if time is a factor.
- The event described in Question 1 of the student worksheet is true. Visit the Mars Climate Orbiter website for more detailed information at http://marsprogram.jpl.nasa.gov/msp98/orbiter/ (accessed August 2009).
- Units are commonly forgotten by students when doing calculations or recording measured data. If this ever happens in your classroom (and it will), simply tell the forgetful student that you would like to borrow $10 and pay back with 10 cents. After all, units do not really matter, do they?
Answers to Questions
- In 1999, the Mars Climate Orbiter spacecraft was lost as it attempted to orbit Mars. According to the investigative report, the main cause was the failure of one team to convert English units to metric. Given the ratios of 1 inch/2.54 centimeters and 10 mm/1 cm, determine how many millimeters are in 8 inches.
- Rudy is attending a party for 15 people, and offered to bring BBQ chicken wings. One bucket of wings has 45 pieces, and Rudy figured on an average of six pieces per person. To find out how many buckets of wings to buy he divided 45 by 6 to get the number of servings in each bucket, and then multiplied that answer by 15 people. His final answer was 112.5. He knew that couldn’t be right. What did Rudy do wrong? How many buckets of wings does Rudy need?
Rudy did not use the correct ratios—his “units” did not cancel out. Following his reasoning, his equation would appear as follows.
Rudy should have done the following calculation.
Since units give dimension to a number, the technique used in this activity is often called dimensional analysis. Some refer to the technique as the factor-label method while others use unit analysis or unit-factor method. No matter what this problem-solving method is called, it is an important tool to use whenever calculations need to be made with measured values.
Whether problems are simple or complex, asking students to simply “label the answer” will not ensure the method used to obtain the solution to the problem was correct. Teachers can reinforce good practice by consistently modeling unit factoring whenever solving problems in front of the class. As students employ the technique of unit factoring—identifying the unknown (target units), specifying what is known (values and units along with relevant conversion factors and units), developing an equation with the appropriate conversion factors, and performing the calculations—they will be developing an essential skill that has many applications in the science classroom and everyday life.
Special thanks to Sue Bober, Schaumburg High School, Schaumburg, IL, for sharing this activity with Flinn Scientific.
Herr, N.; Cunningham, J. B. Hands-On Chemistry Activities with Real-Life Applications; Jossey-Bass: San Francisco, 1999.