Lesson 7

This warm-up prompts students to consider the same object being measured with different length units to set students up to measure with different units in the next activity.

• Groups of 2
• Display the image.
• “¿Qué observan? ¿Qué se preguntan?” // “What do you notice? What do you wonder?”
• 1 minute: quiet think time

• “Discutan con su pareja lo que pensaron” // “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses.

• “¿Alguien puede expresar la idea de ______ con otras palabras?” // “Can anyone restate _____’s idea?”

The purpose of this activity is for students to measure the same length using three different length units. Students choose which units they would like to use. When groups compare their measurements, they notice that although they measured the same length, they got different measurements. They consider why this could be and determine that when they use a different size length unit, they get a different number to describe the length. Some students may notice that the number of units needed depends on the size of each individual length unit, but this is not a discussion point until grade 2.

• Create sets of 30 connecting cubes, 50 base-ten cubes (centimeter cubes), twenty 2-inch paper clips, and twenty 1-inch paper clips for each group.
• Put 18-inch strips of tape on the floor for each group. 

• Groups of 2–4
• Give each group access to the different length units.
• “¿Quién usa los zapatos más grandes en su familia?” // “Who wears the biggest shoes in your family?”
• Share responses.
• “¿Qué tan largos creen que van a ser sus zapatos cuando ustedes sean adultos?” // “How long do you think your shoes will be when you are grown up?”
• Share responses.
• “Un hombre que se llama Jeison Orlando Rodríguez Hernández tiene el récord de tener los pies más largos del mundo. Él tiene que mandar a hacer sus zapatos porque las tiendas no venden zapatos tan grandes” // “A man named Jeison Orlando Rodriguez Hernandez holds the record for having the longest feet in the world. He has to have his shoes specially made because stores don't sell shoes big enough.”

• “En el piso hay cintas que muestran la longitud del pie de Jeison. Ustedes van a medir la longitud del pie de Jeison usando diferentes objetos” // “There are strips of tape on the floor that show the length of Jeison’s foot. You will measure the length of his foot using different objects.”
• Read the task statement.
• 12 minutes: partner work time
• “Comparen sus medidas con las de otro grupo. ¿Qué observan?” // “Compare your measurements with another group. What do you notice?”
• 2 minutes: small group discussion

• “¿Qué observaron cuando midieron el pie de Jeison usando diferentes objetos?” // “What did you notice when you measured the length of Jeison's foot using different objects?”
• If needed, ask, “¿Por qué obtuvimos diferentes números cuando usamos diferentes objetos?” // “Why did we get different numbers when we used different objects?” (The objects we used had different lengths. Some were shorter and some were longer. We used more small cubes to measure the length than any other object.)

The purpose of this activity is for students to use what they have learned about measuring length to determine whether measurements are accurate. Students understand that they need to use same-size units to be precise in their measurements (MP6).

• Groups of 2

• Read the task statement.
• 8–10 minutes: partner work time
• Monitor for students who can explain whose measurements are accurate and whose are not accurate and why.

If students say that Clare's measurement is inaccurate because she did not use connecting cubes or because the measurement is not 15, encourage students to tell you more about what they mean. Consider asking:

• “¿En qué se parece la forma en que Clare midió a la forma en que nosotros medimos objetos en la actividad anterior?” // “How is the way Clare measured like how we measured objects in the last activity?”
• “¿Clare midió toda la longitud del zapato con los bloques pequeños?” // “Did Clare measure the entire length of the shoe with the small blocks?”
• “¿En qué se parecen los bloques pequeños? ¿En qué son diferentes?” // “How are the small blocks the same? How are they different?”

• Display the image for Jada’s measurement.
• “¿La medida de Jada es precisa? ¿Por qué sí o por qué no?” // “Is Jada’s measurement accurate? Why or why not?” (It is not accurate because there are gaps between some of the cubes.)
• Display the image for Kiran’s measurement.
• “¿La medida de Kiran es precisa? ¿Por qué sí o por qué no?” // “Is Kiran’s measurement accurate? Why or why not?” (Kiran’s measurement is not accurate because the cubes are different sizes.)
• “¿Qué podría cambiar Kiran para que su medida sea precisa?” // “What could Kiran change to make his measurement accurate?” (He could use all connecting cubes or all the little cubes, instead of using some of each.)
• “Cuando medimos una longitud con objetos, es importante que cada objeto tenga la misma longitud” // “When we measure a length with objects it is important that each object has the same length.”