The purpose of this activity is for students to apply what they know about multiplication and division to solve problems involving the volume of the wagon bed. Students estimated the dimensions and volume of the big red wagon in the previous lesson, and now they learn the actual dimensions and solve problems with those dimensions. The context in this activity is filling the big red wagon with sand. Students will use multiplication and division to find how many bags of sand it will take to fill the wagon, and then they find the cost and weight of all of that sand (MP2). The Activity Synthesis focuses on a strategic way to calculate the number of bags of sand it takes to fill the wagon.

To add movement to this activity, students could create a poster for the problems and do a Gallery Walk to look for similarities and differences in the strategies used to multiply and divide.

• Invite students to share their responses for the number of bags of sand it takes to fill the wagon.
• Display expression:
• “¿Cómo está representado en la expresión el número de bolsas de arena que se necesitan para llenar el gran remolque rojo?” // “How does this expression represent the number of bags of sand it takes to fill the wagon?” (The product is the number of cubic feet the wagon holds, and each bag of sand fills 9 cubic feet, so dividing by 9 gives the number of bags of sand needed to fill the wagon.)
• “Jada dice que puede encontrar rápidamente el valor de la expresión si encuentra primero el valor de . ¿Su estrategia funcionará? ¿Cómo lo saben?” // “Jada says that she can find the value of the expression quickly by first finding the value of . Will her strategy work? How do you know?” (Yes, it will work. Rather than finding the product of all 3 numbers and then dividing by 9, Jada notices that she can just divide 27 by 9 and that’s 3. Then she just needs to multiply 3 by 13 and 2 which is easier since they are smaller numbers.)

The purpose of this activity is for students to solve another problem about the big red wagon using multiplication and division. Instead of filling the wagon with sand, they consider filling the wagon with boxes and determine how many boxes will fill the wagon. Unlike with the sand, the boxes do not fill the wagon completely and the number of boxes that do fit is not a divisor of the total number of boxes. Accounting for these considerations will be the focus of the Activity Synthesis. When students account for these constraints of the situation, they persevere in solving the problem (MP1).

• Invite students to share their responses for the number of trips.
• “¿Cómo encontraron cuántas cajas le caben al remolque?” // “How did you find how many boxes will fit in the wagon?” (I counted how many rows of boxes I could fit and how many were in each row.”
• “¿El remolque se llenó con las cajas?” // “Did the boxes fill the wagon?” (No, the length and width of the wagon are odd and the boxes are all 2 feet wide and long so there is 1 foot of empty space left on both sides.)
• “¿Creen que pueden meter más cajas y así hacer menos viajes?” // “Do you think you could fit more boxes and make fewer trips?” (Yes, I could fit those extra 22 boxes along the side where it is not full in some of those 51 other trips. I would just need to be careful so they don't fall over the side.)