The purpose of this activity is to represent and solve a measurement problem with fractions. Students may approach this activity in multiple ways and are invited to apply what they know about operations with fractions, comparing fractions, and fraction equivalence to make sense of and solve the problems (MP2). Throughout the activity, listen for the ways students use what they know about comparing fractions and fraction equivalence as they make sense of the problem. Although students may consider ways to subtract fractions with unlike denominators, this is not a requirement for grade 4. Focus the conversation during the activity and the Activity Synthesis on how students can solve the problem by reasoning about equivalent fractions and on the representation they use to make sense of the problem.

• “¿Cómo se ve la longitud de la pajilla en tu representación? ¿Cómo se ven los pedazos de Noah y de Tyler?” // “How does your representation show the length of the straw? How does it show Noah's and Tyler’s pieces?”
• “¿Cómo se ve la acción de la situación en tu representación?” // “How does your representation show the action in the situation?”

• Invite previously selected students to share their arguments and allow the class to extend and add ideas to the conversation.
• “¿Qué relación hay entre cada representación y esta situación de la pajilla?” // “How does each representation match this situation about the straw?” (Each shows the total length of the straw and ways it could be broken into smaller parts. Each shows the length of Noah’s and Tyler’s pieces. They show how long Jada’s piece could be.)

In this activity, students practice solving word problems that involve adding and subtracting mixed numbers. Students interpret fractions in the context of comparing heights and use what they know about decomposing whole numbers and equivalent fractions to make sense of and solve each problem (MP2). Look for the different ways students use what they know about the structure of whole numbers and fractions as they reason about how to solve each problem and share their thinking with others.

• “¿Cómo hallaste la estatura de _____?” // “How did you solve for _____'s height?”
• “¿Cómo puedes usar un diagrama como ayuda para representar las distintas estaturas que hay en este problema?” // “How could you use a diagram to help you represent the different heights in this problem?”

• Invite students to share their equations and explain their solution for Lin’s height.
• Display:

• “¿Cómo podrían pensar en una forma de encontrar el valor de la estatura de Lin?” // “How might you reason about how to find the value of Lin’s height?” (Think about adding to  to make 51, then it'd be . We are adding more than 1 because  is more than . or , and )

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• Select students to share both addition and subtraction equations for Mai’s current height and discuss how both equations ( and ) could be used to represent this situation.