Disappearing Cookies
Task
Kathy had fun baking lots of cookies. She left them on a plate to cool while she went shopping with her dad. Her brother saw the cookies and took 1/2 of them to his Scout meeting. Her sister took 2/3 of the remaining cookies to share with her friends. Finally, her mom took 1/2 of the remaining cookies to her Book Club meeting. When Kathy and her dad got home, there were only 5 cookies left on the plate.
How many cookies had Kathy baked?
Alternate Versions of Task
| More Accessible Version:
Kathy had fun baking lots of cookies. She made 24 of them, leaving them on a plate to cool while she went shopping with her dad. Her brother saw the cookies and took 1/2 of them to his Scout meeting. Her sister took 1/4 of the remaining cookies to share with her friends. Finally, her mom took 1/3 of the remaining cookies to her Book Club meeting. When Kathy and her dad got home, how many cookies were left on the plate?
More Challenging Version:
Go to the library and sign out a cookbook that has a recipe for chocolate chip cookies. Use the recipe to determine the exact amount of each ingredient Kathy used to make the cookies.
|
Context
This task was piloted in a fourth-grade classroom.
What This Task Accomplishes
This task allows the teacher to assess students' understanding of fractions and the problem-solving strategy of working backwards to solve a problem.
Time Required for Task
45 minutes
Interdisciplinary Links
This task could link to a unit on cooking.
Teaching Tips
To make the task more complicated, you can change the fractions presented in the task.
Suggested Materials
Manipulatives (students can use to represent cookies)
Possible Solutions
There were 60 cookies to begin with.
| More Accessible Version Solution:
24 x 1/2 = 12 left
12 x 3/4 = 9 left
9 x 2/3 = 6 left on the plate
More Challenging Version Solution:
The solution will depend of the recipe the student finds. To determine accuracy, divide the number of cookies the recipe makes by the number of cookies Kathy makes. Multiply each ingredient in the recipe by this amount.
|
Task Specific Assessment Notes
Novice:
The student is unable to proceed toward a solution. Little or no math language is used. Representations may be attempted.
Apprentice:
Little math language is used. A partial solution is achieved, but all parts of the task are not attempted or are attempted unsuccessfully. Representations are used to organize the solution.
Practitioner:
The student has an approach that works and achieves a correct solution. Representations are used to organize the solution. Work is shown and labeled. Math language is used to communicate.
|
Expert:
The student has an approach that works and achieves a correct solution. Sophisticated math language is used to communicate. Representations are used to organize the solution. The student demonstrates solid understanding of fractions.
|
