Gallery Problems

Gallery Problems

Stew Recipe

Work Time

Stew Recipe

Molly’s recipe for stew says to use 34 pound of potatoes per person. Molly has 24 pounds of potatoes. Molly wonders if she can make enough stew to serve all 36 people at her party.

  1. Calculate 36×34. What information can Molly get from the answer?
  2. Calculate 24÷34. What information can Molly get from the answer?
  3. Will Molly have enough potatoes? If not, how many more pounds will she need?

Multiply or Divide?

Work Time

Multiply or Divide?

  1. Daniela has a ribbon 312 feet long. Consider the following expressions:

    312÷34
    312×34


    a) Which expression represents the number of pieces she would have if she cut the ribbon into 34-foot pieces?

    b) Which expression gives the length of 34 of the ribbon in feet?

  2. A recipe calls for 223 cups of flour. Consider the following expressions:

    223÷13
    223×13


    a) Which expression represents the amount of flour in 13 of a recipe?

    b) Which expression represents the number of times a 13 cup measure would need to be filled to measure the flour?

  3. Ji Young made 512 pounds of pasta salad. Consider the expressions below.

    512÷18
    512×18


    a) Tell what the expression 512÷18 could represent in this situation.

    b) Tell what the expression 512×18 could represent in this situation.

Card Sort

Work Time

Card Sort

Work with a partner.

Take turns finding the expression card, diagram card, and answer card that matches each problem.

Explain to your partner how you know that the cards match the problem.

Your partner should either agree with your explanation or challenge it if he or she thinks your explanation is not correct, clear, or complete.

For each matched set, explain what the solution card represents.

INTERACTIVE: Card Sort

Complex Fractions

Work Time

Complex Fractions

A complex fraction is a fraction whose numerator and/or denominator contain fractions. Here are some examples of complex fractions:

345

473 2358

You can change a complex fraction to a regular fraction by multiplying it by 1 in a form that “clears” the fractions.

2358=2358×2424=4831208=1615

You can use this idea to divide fractions.

Consider the problem 34 ÷ 56.

  1. Write the division problem as a complex fraction.

  2. Multiply the complex fraction by 1 in a form that will clear the fractions in the numerator and denominator, giving a regular fraction. The result is the solution to 34 ÷ 56.

  3. Use multiplication to check that the result from Part 2 is the solution to the division problem.

  4. Use the complex fraction method to find 213 ÷ 12. (You will need to write 213 as a fraction.)