Lesson 23

The purpose of an Estimation Exploration is to practice the skill of estimating a reasonable answer based on experience and known information.

• Groups of 2
• Display the image.
• “El grupo encerrado en un círculo muestra 10 frijoles” // “The circled group shows 10 beans.”
• “¿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

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

• Select one “about right” estimate.
• “Usando decenas y unidades, ¿de qué formas podemos pensar en este número?” // “What are some ways we can think about this number using 10s and 1s?”

The purpose of this activity is for students to have an opportunity to apply their place value understanding to estimate quantities of objects and accurately count familiar objects.

• Each group of 2 needs a bag of a collection of small objects. 

• Groups of 2
• Display for all to see approximately 15–25 beans or other small objects.
• “¿Cuántos objetos piensan que hay en este montón?” // “How many objects do you think are in this pile?”
• 1 minute: partner discussion
• Share responses.
• “¿Cómo podemos encontrar cuántos hay exactamente?” // “How could we find out exactly?” (Count them.)

• “¿Cuántos objetos hay en 2 puñados? Hagamos un experimento” // “How many objects are in 2 handfuls? Let's do an experiment.”
• Give each group a bag of objects.
• “Cada uno agarre un puñado. Estimen cuántos objetos agarraron ambos en total. Después, encuentren exactamente cuántos objetos tienen” // “Take turns and grab a handful. Estimate how many objects you both grabbed altogether. Then find out how many you have exactly.”
• “Van a hacer este experimento tres veces” // “You will do this experiment three times.”
• 5 minutes: partner work time
• Monitor for students who:
  • count by ones
  • group the objects into groups of 10 and then count the tens and ones

• Invite previously identified students to share.
• “¿Sus estimaciones mejoraron con la práctica?” // “Did your estimates get better with practice?”
• “¿Cómo les ayudó organizar sus objetos a contar?” // “How did organizing your objects help you to count?”
• “Imaginen que tengo 72 objetos. ¿Cuántos tendrían si tienen 10 menos que yo? ¿Y si tuvieran 10 más?” //  “Imagine I have 72 objects. How many would you have if you have 10 fewer than I do? What if you had 10 more?”
• “Si tuvieran 72 objetos, ¿cómo se pueden organizar en montones de 10 y unidades? ¿Hay otras formas?” // “If you had 72 objects, how could they be arranged in piles of 10 and ones? Are there any other ways?" (7 tens and 2 ones, 6 tens and 12 ones)

The purpose of this activity is for students to consider the number of objects in a group and represent numbers in as many ways as possible. Students should be encouraged to think about the number in terms of tens and ones. Students sort pictures based on the number of objects they estimate to be in each group.

Students should be encouraged to estimate quantities rather than try to count them. Some students may not have a reasonable estimate, but can be successful in this activity if they categorize the photograph based on whatever estimate they consider is “about right.”

• Create a set of cards from the blackline master for each group of 2.

• Groups of 2
• Give each group a set of cards.

• • “Hay una imagen diferente en cada tarjeta. Clasifiquen las tarjetas según el número de objetos que piensan que hay en cada imagen” // “There is a different picture on each card. Sort the cards based on the number of objects you think are in each picture.”
  • 8 minutes: partner work time
  • As students work, consider asking:
    • “¿Qué estimación sería muy baja?, ¿razonable?, ¿muy alta?” // “What is an estimate that is too low, about right, and too high?”

• Invite students to share what object they selected and its representation.
• Record responses.
• Select two estimates that have the same digit in the ones place.
• “¿Cómo sabemos cuál estimación es más grande?” // “How do we know which estimate is bigger?”
• Highlight the use of ones and tens.