Kids in the Kitchen (Fractions/Multiplication)

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Baking and cooking are great ways to have children work with numbers (especially fractions) and measurement in a meaningful way.

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Here are some possible discussions to have with children when baking/cooking:

• Discuss the different measuring cups and spoons you are using and compare the sizes
• Which cup is biggest? Which cup is smallest?  Is the 1/2 cup or 1/3 cup bigger?
• How many 1/4 cups of sugar would we need to make a whole cup?  Test it out!

• Discuss the ways to measure different ingredients
• What measuring tools are typically used for dry ingredients? Liquid ingredients?
• A liquid measuring cup usually has measurements for cups, as well as ounces
• Are there any other ways you have seen liquids measured before [thinking the metric system - liters (L), milliliters (mL)]?

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• Discuss other measurements used in the kitchen
• In addition to cups, foods can also be measured in pints, quarts, and gallons (use Gallon Man, at right, to help remember the relationships between these measurements), or by weight (pounds and ounces)

• When looking at recipes, discuss how many servings or items the recipe should yield
• A cookie recipe might yield 2 dozen cookies
• How many cookies is that?
• What would we need to do to the ingredients in the recipe if we only wanted 1 dozen cookies? What about if we wanted 4 dozen cookies? 5 dozen?
• Sometimes there can be situations trickier than halving or doubling a recipe
• Recently, I made Maple Butternut Squash Puree.  The ingredient list is below on the left.  I needed to do some calculating to figure out how to make more servings for a large family dinner (see image below on the right).

• I had bought two butternut squashes at the grocery store, totaling 5.8 pounds according to my receipt.  Since the original recipe called for 3 1/2 pounds of squash I needed to figure out what to multiply each ingredient amount by in order to proportionally change the other ingredients in the recipe.
• I chose to convert 5.8 pounds to a fraction (see previous post from 4/4/15 for more on that!) and subtract 6 ounces (3 oz for each squash that are lost when peeled).  Then I rounded to the nearest half pound and subtracted to find that I had two extra pounds, meaning that I had 1 2/3 times the amount of squash that is called for in the original recipe.  I was then able to multiply each ingredient by 5/3 to find the new amounts I needed to measure for the larger recipe.

• HOME/SCHOOL ACTIVITY
• Have children find copies of their favorite recipes, then have them use those recipes to complete the Recipe Worksheet posted on my Worksheets/Solutions page.
• The numbers on the worksheet can be modified for different ages/grades or in order to differentiate for different abilities in the classroom.

Age/Grade Guidelines:

In Massachusetts, the Common Core State Standards have been adopted.  Multiplication of fractions is a 5th grade standard.  In order to change the amounts of ingredients needed in a recipe, children will need to be able to multiply a fraction or whole number by a fraction (CCSS.MATH.CONTENT.5.NF.B.4).  It would also help for children to understand that one can get a smaller product by multiplying by a fraction smaller than 1 (CCSS.MATH.CONTENT.5.NF.B.5.B).  Additionally, children show that they are able to solve real life math problems and show the math work necessary to calculate the answer (CCSS.MATH.CONTENT.5.NF.B.6).

How much does a 7 month old weigh? (Subtraction/Regrouping/Conversions)

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My daughter, Hannah, recently had her seven-month birthday.  We have been taking a photo of her each month in her children's armchair with her giraffe stuffed animal, and putting them in a small album.  In addition to the picture, we record Hannah's weight and height, as well as some memorable moments from the past month.  Since we don't go to the doctor each month, I need to weigh Hannah myself in order to record her stats.  Our bathroom scale cannot measure such a light person, so we had to come up with another strategy besides sitting Hannah on our scale.  Another point to mention about a baby's weight and our scale, is that the doctor measures the baby's weight in pounds and ounces, while the scale measures by two tenths of a pound, in decimals.  From this scenario, I ended up coming up with several ways math skills are used to calculate Hannah's weight.  Below, I have grouped some questions by skill.  In the document on my Worksheets/Solutions page, there is a multi-step math problem incorporating the categories below.  Different groupings of these questions (or different numbers) could be used for different ages/grades or to allow for differentiation for different abilities in the classroom.

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Logic/Problem-Solving

• I wanted to be able to weigh Hannah in between doctor's appointments, but did not have a scale that could measure such a light person.
• How could I use a regular adult bathroom scale to measure Hannah's weight?

Conversions

• At the doctor's office, the nurse measures Hannah in pounds and ounces (example: Hannah weighed 6 pounds, 12 ounces when she was born).  However, my bathroom scale measures in pounds, with decimals that go up by two tenths (0.2).
• How could I use the bathroom scale to measure in pounds and ounces?
• What is an important piece of information you need to know in order to be able to solve this problem?
• According to my scale, I weigh 139.4 pounds.  Approximately, how many pounds and ounces is this?
• According to my scale, if I weigh myself while I am holding Hannah, we weigh 156.2 pounds total.  Approximately, how many pounds and ounces is this?

Subtraction with REGROUPING

(previously referred to as "borrowing")

• Using the decimal numbers given by the scale, how much does Hannah weigh?
• Using the conversions above, approximately how much does Hannah weight in pounds and ounces?
• Are the two answers above equivalent?  Why or why not?
• Check out THIS VIDEO for a tutorial on regrouping, in the base-10 number system, as well as with pounds & ounces, feet & inches, and with mixed numbers

**You can find an editable/printable version (using Word) of the above questions, along with solutions, on my Worksheets/Solutions page.

Age/Grade Guidelines:

In Massachusetts, the Common Core State Standards have been adopted.  Subtraction with regrouping is introduced in second grade (CCSS.MATH.CONTENT.2.NBT.B.7), and an algorithm for this is solidified by the end of fourth grade (CCSS.MATH.CONTENT.3.NBT.A.2, CCSS.MATH.CONTENT.4.NBT.B.4).  The skills necessary to complete the conversions in this scenario are introduced in fourth grade (fraction/decimal equivalence [CCSS.MATH.CONTENT.4.NF.C.6], multiplication with fractions [CCSS.MATH.CONTENT.4.NF.B.4]) and solidified during elementary school.  
The multi-step math problem on the Worksheets/Solutions page uses skills learned in elementary school; however, seeing as these skills need to be synchronized to reason about and calculate solutions, the problem (as written) would be appropriate for a challenging upper elementary, or middle school assignment.  As previously mentioned, different groupings of these questions (or different numbers) could be used for different ages/grades or to allow for differentiation for different abilities in the classroom.