Ask students to think back to their original estimates
of the number of buttons in their bags. Have student
pairs decide an efficient way to count their buttons,
place the buttons in groups, and find the exact number
of buttons. Ask for volunteers to tell their estimates
and their actual counts. Discuss the process of
making an estimate and evaluating whether it was a
reasonable one or not.
- Do you think your estimate was a good one? Was it close to your actual count? How close?
- How did you arrive at the number you chose as your estimate? (Possible response: I compared it
to the benchmark bags and it looked the closest to 50 buttons.)
- Had you ever made an estimate (guessed a quantity)
before? Did that experience help you? How?
- What information did you use? (Possible
response: I knew my bag had more than the bag
of 20 but less than the bag of 80. It looked like it
had about 50, so my estimate was 55.)
- How did you group your buttons to count them?
(Possible response: We grouped them by tens.
We had 4 groups of ten and 3 leftovers. We skip
counted the 4 groups by tens and counted the 3
leftovers by ones to find the total.)
Remind students that a close estimate is a good estimate
and that their estimates will probably not be
exact.
Use the All Sorts of Buttons pages and the related discussion
to assess students’ abilities to use a benchmark to estimate a
quantity of objects in a collection [E4]; use efficient grouping
strategies to count a collection of objects [E3]; and sort
objects by their characteristics [E8].
