At Mai’s school, there are 358 students in second grade and 465 students in third grade.

About how many students are in the second and third grades altogether?

Record an estimate that is:

There are 227 students in kindergarten and 378 students in first grade at Mai’s school.

Her classmates made some estimates about the total number of students in kindergarten and first grade.

Work with your partner. Decide which estimates make sense. Give 1 way each person could improve their estimate.

1. Jada: 500 students, because 2 hundreds and 3 hundreds is 5 hundreds.

   1. Does it make sense? Explain your reasoning to your partner.
   2. If not, how could Jada improve her estimate?

2. Lin: 100 students, because 3 hundreds take away 2 hundreds is 1 hundred.

   1. Does it make sense? Explain your reasoning to your partner.
   2. If not, how could Lin improve her estimate?

3. Andre: 600 students, because 227 is close to 225 and 378 is close to 375. , , and .

   1. Does it make sense? Explain your reasoning to your partner.
   2. If not, how could Andre improve his estimate?

1. For each expression, decide whether the actual value is greater than or less than the estimate.

   1. Is the value of greater than or less than 600?
   2. Is the value of greater than or less than 400?

2. Work with your partner to find the actual value.

3. Find the value of 1 of the expressions. Explain or show your reasoning.

4. Trade work with a partner. Decide whether your partner’s value for the expression makes sense. Explain your reasoning.