Not all roles available for this page.
Sign in to view assessments and invite other educators
Sign in using your existing Kendall Hunt account. If you don’t have one, create an educator account.
The purpose of this Number Talk is for students to demonstrate strategies and understandings they have for using the properties of operations when multiplying whole numbers and mixed numbers. These understandings help students develop fluency and will be helpful later in this lesson when students will flexibly multiply.
Find the value of each expression mentally.
The purpose of this activity is for students to consider situations and the operations involved in order to select reasonable numbers for each situation. Students are given a set of numbers which must each be used once in the statements. Students may find that their initial thinking does not work with the given constraints and they may need to revise their work (MP1). They also need to think carefully about the units involved and consider whether a number is representing a linear unit or a square unit. Students may solve these problems using several different strategies.
Write 1 number from the list in each blank so the situations make sense. Each number can be used only once.
4
5
3
The area of a rectangular rug is square feet. The length of the rug is ___________ feet.
The width of the rug is ___________ feet.The area of a rectangular whiteboard is 23 square feet. The length of the whiteboard
is _________ feet. The width of the whiteboard is ________ feet.Share your work with your partner. Explain what choices you made and why.
The purpose of this activity is for students to match different diagrams and expressions representing the same product. In the previous several lessons, students have studied different ways to find products of a whole number and a fraction using arithmetic properties such as the distributive property. Earlier in the unit they learned about the connection between fractions and division. Students combine these skills as the expressions and diagrams they work with incorporate both the distributive property and the interpretation of a fraction as division (MP7). Students may match diagrams to expressions differently than the ways that are listed in the Sample Responses. Encourage students to match the expressions and diagrams in a way that makes sense to them, as long as they can accurately explain how the expression is represented in the diagram they chose.
MLR7 Compare and Connect. Invite students to prepare a visual display that shows their thinking about their favorite diagram and expression. Encourage students to include details that will help others understand what they see, such as using different colors, arrows, labels, or notes. If time allows, invite students to investigate each others’ work.
Advances: Representing
“Today we used what we have learned to find the value of expressions involving multiplication of whole numbers and fractions greater than 1 written as mixed numbers.”
Display .
“Tell me everything you know about this expression.” (It is equal to a number between 42 and 48. It is equal to and to . We can draw an area diagram to represent .)
Record student responses.
If not mentioned by students, record an area diagram and equivalent expressions.
We learned how to find the area of a rectangle with a fractional side length.
Example: The shaded region has an area of because there are 4 groups of of a square unit shaded. The area is or because there are 8 shaded parts and each one is of a square unit.
We also learned to multiply a mixed number by a whole number. We used diagrams and expressions to see why our strategies work.
Example: To multiply , we can use the expression . We can see both expressions represented by the shaded region in the diagram.
So, the area of the shaded region is or square units.
Each diagram represents a way to calculate .
Each expression is equivalent to .
Match each diagram to an expression. Explain or show your reasoning.
Choose your favorite diagram and expression to find the value of . Be prepared to explain why it is your favorite.