The purpose of this activity is for students to round given numbers to the nearest ten and the nearest hundred to see that the result can be the same for some numbers. Students think about what it means to round a number that is exactly halfway between two tens or two hundreds, and are introduced in the Activity Synthesis to the convention that these numbers are rounded up (MP3).

• Select previously identified students to share their responses.
• “Kiran y Priya tienen razón. No hay solo un múltiplo de 10 que sea el más cercano a 415 porque este número está justo en el medio de dos múltiplos de 10. No hay solo un múltiplo de 100 que sea el más cercano a 750 porque este número está justo en el medio de dos múltiplos de 100” // “Kiran and Priya are correct. There isn’t one closest multiple of 10 to 415 because it’s right in the middle of two multiples of 10. There isn’t one closest multiple of 100 to 750 because it’s right in the middle of two multiples of 100.”
• “En casos como este, redondeamos hacia arriba. Por ejemplo, 415 está en el medio entre 410 y 420. Entonces para redondear 415 a la decena más cercana, lo redondeamos hacia arriba, a 420” // “In cases such as this, we round up. For example, since 415 is halfway between 410 and 420, we round up to 420 when rounding to the nearest ten.”
• “Como 750 está en el medio entre 700 y 800, lo redondeamos hacia arriba, a 800” // “Since 750 is halfway between 700 and 800, we round up to 800.”
• “En ambos casos, podríamos decidir hacerlo de la otra forma, pero es útil que todos hagamos lo mismo” // ”In both situations, we could go the other way, but it is helpful if we all do the same thing.”

The purpose of this activity is for students to practice rounding to the nearest ten and the nearest hundred in context. Students work with numbers from a previous lesson to estimate the total number of students in a school. They learn that how a number is rounded (to the nearest ten or to the nearest hundred) can give different estimates for the same situation.

• Invite students to share their observations about the completed table, including whether it matched their predictions.
• “Al estimar un total, redondear a la decena más cercana puede darnos un resultado distinto al de redondear a la centena más cercana. Si redondean para estimar un total, ¿redondearían a la decena más cercana o a la centena más cercana?” // “When we are estimating a total, rounding to the nearest ten or the nearest hundred can give us different results. If you were rounding to estimate a total, would you round to the nearest ten or the nearest hundred?” (The nearest ten because you get an estimate that’s closer to the total. The nearest hundred because multiples of 100 are easier to work with.)
• “Tengan estas ideas presentes mientras redondean para hacer estimaciones en las próximas lecciones” // “Keep these ideas in mind as you use rounding to estimate in future lessons.”