The purpose of this Estimation Exploration is to practice the skill of estimating a reasonable answer based on experience and known information. The Warm-up also draws students' attention to a length between a full inch and one-half of an inch, preparing students to work with such lengths later.
Launch
Groups of 2
Display the image.
“¿Qué estimación sería muy alta?, ¿muy baja?, ¿razonable?” // “What is an estimate that’s too high? Too low? About right?”
1 minute: quiet think time
Activity
“Discutan con su compañero cómo pensaron” // “Discuss your thinking with your partner.”
1 minute: partner discussion
Record responses.
¿Cuál es la longitud del clip?
Escribe una estimación que sea:
muy baja
razonable
muy alta
Student Response
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Advancing Student Thinking
Activity Synthesis
Consider asking:
“¿Alguien hizo una estimación menor que _____? ¿Alguien hizo una estimación mayor que _____?” // “Is anyone’s estimate less than _____? Is anyone’s estimate greater than _____?”
“Teniendo en cuenta esta discusión, ¿alguien quiere ajustar su estimación?” // “Based on this discussion, does anyone want to revise their estimate?”
Activity 1
Standards Alignment
Building On
Addressing
3.MD.B.4
Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units–-whole numbers, halves, or quarters.
The purpose of this activity is for students to partition the inches on a ruler into fourths, or quarters of an inch, using what they know about fractions on a number line. Students then use the ruler to measure objects in the classroom to the nearest quarter inch. In the Activity Synthesis, students practice reading the measurements as fractions greater than 1 and as mixed numbers. They also discuss how measuring in fourths of an inch is different than measuring in half inches.
Students will use the rulers they partition in the next activity.
MLR2 Collect and Display. Direct attention to the words collected and displayed during the previous lesson. Invite students to borrow language from the display as needed, and update it throughout this lesson with numbers, words, and phrases, such as “ocho cuartos”, “”, “cinco y un cuarto pulgadas”, “menos de cinco y media pulgadas” // "eight fourths," "," "five-and-one-fourth inches," and "less than five-and-one-half inches."
Advances: Conversing, Reading
Launch
Groups of 2
Display the image.
“¿Todos están de acuerdo en que este clip mide pulgadas de largo? Expliquen cómo razonaron” // “Would everyone agree that this paper clip is inches long? Explain your reasoning.” (No. It ends in between the 1 inch mark and the inch mark. No. It looks like it’s inches, because if we partition a half into 2 equal parts, it’s a quarter inch. It depends on how we’re measuring. If we measure to the nearest inch or half inch, it’s 1 inch long, but to the nearest quarter inch, it’s 114 inches long.)
1 minute: partner discussion
Share responses.
“¿Cómo podemos obtener una medida que sea más cercana a la longitud del clip?” // “How can we get a measurement closer to the length of the paper clip?“ (We can partition the half inches into smaller parts. We can measure in fourths.)
Make sure each group has a ruler that didn't get partitioned from the previous lesson.
Activity Synthesis
Invite previously identified students to share an object and its length in quarter inches.
For each measurement, ask the class to repeat the measurement as a fraction greater than 1 and as a mixed number or whole number.
As needed, explain that when measuring to the nearest quarter inch, the result can be a whole number of inches. For example, if an object's length is closer to 2 inches than to , its length to the nearest quarter inch is 2 inches (or inches).
“¿Qué diferencia hay entre medir longitudes en cuartos de pulgada y medirlas en mitades de pulgada?” // “What’s different about measuring lengths in quarter inches and measuring in half inches?” (With quarter inches, it was more likely for the length of the object to match or be close to a mark on the ruler than to fall between two marks. There were also more marks to use to measure.)
Activity 2
Standards Alignment
Building On
Addressing
3.MD.B.4
Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units–-whole numbers, halves, or quarters.
The purpose of this activity is for students to practice measuring objects in the classroom using their partitioned rulers and find objects of certain fractional lengths. Because the specified lengths are in halves and fourths of an inch, students may use both rulers. As students realize that all lengths could be measured with the rulers showing fourths of an inch, they may opt to use only one ruler.
When students decide to measure in halves or fourths of an inch based on the length of an object, they attend to precision (MP6).
Representation: Internalize Comprehension. Synthesis: Invite students to identify which details were most useful to measure accurately. Display the sentence frame, “La próxima vez que mida objetos con una regla, buscaré . . .” // “The next time I measure objects with a ruler, I will look for . . . .“ Supports accessibility for: Memory, Conceptual Processing
Launch
Groups of 2
“Ahora van a usar las reglas que ya tienen la partición para encontrar objetos que tengan ciertas longitudes, en pulgadas” // “You’ll now use the rulers you partitioned to find objects that have certain lengths in inches.”
“Tómense un minuto para leer las instrucciones y mirar las longitudes que están en la tabla” // “Take a minute to read the instructions and look at the lengths in the table.”
1 minute: quiet think time
Invite 1–2 students to explain the activity in their own words. Answer any questions students might have.
Activity
“Completen la actividad con su compañero. Asegúrense de practicar juntos cómo se dice cada medida” // “Work with your partner to complete the activity. Be sure to practice saying each measurement with your partner.”
“Si encuentran un objeto que tenga una longitud descrita en una de las últimas cuatro filas de la tabla, asegúrense de escribir la medida” // “If you find an object with the length described in the last four rows of the table, be sure to write down the measurement.”
10–12 minutes: partner work time
En esta actividad, van a necesitar las reglas que ya tienen una partición en medios y cuartos de pulgada.
Con su compañero:
Encuentren al menos 4 objetos del salón que tengan las longitudes que se muestran en la tabla.
Practiquen cómo decir cada medida.
Anoten el objeto en la tabla. Si encuentran un objeto que mida un número entero más una fracción de pulgada, escriban la medida exacta.
objeto
longitud
pulgadas
pulgadas
pulgadas
pulgadas
un número entero de pulgadas
un número entero y pulgadas
un número entero y pulgadas
un número entero y pulgadas
Activity Synthesis
Invite 3–4 students to share an object and the length of the object. Record each measurement and ask the class to say it together.
“¿Cómo decidieron cuál regla usar (la que está partida en mitades de pulgada o la que está partida en cuartos de pulgada)?” // “How did you decide which ruler to use—the one partitioned in half inches or the one partitioned into fourth or quarter inches?” (For lengths that are whole numbers or show inch, we used the ruler partitioned into halves. For lengths that show , , or , we used the ruler partitioned into fourths. We used only the ruler partitioned into fourths because we can see whole numbers, halves, and fourths in it.)
Consider asking: “¿Hubo alguna medida en particular que haya sido fácil de encontrar porque muchos objetos tienen esa longitud? ¿Hubo alguna que haya sido difícil de encontrar?” // “Was there a particular measurement that was easy to find because a lot of objects have that length? Were there any that were hard to find?”
Lesson Synthesis
Display a ruler with whole-inch marks, a ruler with half-inch marks, and a ruler with quarter-inch marks.
“Si quisieran medir y obtener una longitud que fuera lo más cercana posible a la longitud real del objeto, ¿cuál regla usarían? ¿Por qué?” // “Which ruler would you use if we want to measure and get a length that is as close as possible to the actual length of the object? Why” (I would use the ruler with quarter inches because they would allow me to get really close to the actual length of the object. The smaller unit makes it easier to get a more accurate measurement.)
Standards Alignment
Building On
Addressing
3.MD.B.4
Generate measurement data by measuring lengths using rulers marked with halves and fourths of an inch. Show the data by making a line plot, where the horizontal scale is marked off in appropriate units–-whole numbers, halves, or quarters.
“Tienen una regla a la que no le hicieron ninguna partición en una lección anterior” // “You have a ruler that was not partitioned in an earlier lesson.”
“Con su compañero, hagan una partición de esa regla para mostrar cuartos de pulgada. Después, cada uno va a escoger dos objetos para medirlos al cuarto de pulgada más cercano” // “Work with your partner to partition that ruler to show fourths of an inch. Then you will each choose two objects to measure to the nearest quarter inch.”
“Cuando partimos una pulgada en cuartos, podemos llamar las partes ‘cuartos de pulgada’” // “When we partition an inch into fourths, we can call the parts ‘fourths of an inch’ or ‘quarters of an inch’ or ‘quarter inches.’ They mean the same thing.”
5–7 minutes: partner work time
Monitor for students who find measurements that are a whole number of inches and those that find measurements that include a whole number and quarter inches.
Van a necesitar una regla que no tenga la partición de la actividad anterior.
Con su compañero, hagan la partición de la regla para mostrar cuartos de pulgada.
Por turnos, usen esta regla y midan la longitud de algunos objetos del salón. Midan cada longitud al cuarto de pulgada más cercano.
objeto
longitud
Student Response
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Advancing Student Thinking
If the parts students partitioned aren’t equal, consider asking:
“¿Cómo partiste las pulgadas en cuartos?” // “How did you partition the inches into fourths?”
“Si partes primero en mitades de pulgada, ¿cómo te puede ayudar eso a partir en cuartos de pulgada?” // “How could partitioning into half inches first help partition into quarter inches?”