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. Students 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.

• “¿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 accurate and precise in their measurements (MP6).

• 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 small cubes, instead of using some of each. He could say how many connecting cubes and how many small cubes he used.)
• “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.”