- Estimate the number of objects in collections of up to 200 and verify their estimates by counting.
- Round whole numbers to the nearest ten or hundred, in various contexts.

- Students practice estimation skills in the context of various birthday party scenarios.
- Students should be comfortable with rounding whole numbers based on context.

- Book:
*Moira’s Birthday*by Robert Munsch- Jar of small items (e.g. pencils, erasers, beans)

- Jar of small items (e.g. pencils, erasers, beans)
- Appendix A (Slideshow)

Introduction:

- Prepare a jar of small items before starting the lesson (see materials).
- Show students the jar of items lesson and ask them to estimate the number of items in it. Ask what strategies they use for estimating quantities.
- Invite students to share their understanding of the word “estimation”.
*An estimate is a number that is reasonably close to the right answer. Estimation is a powerful tool for planning because it can help you quickly determine a numerical quantity that is close to the answer.*

- Ask students the following questions to support their understanding of estimation.
*Have you ever estimated anything? What do we estimate?*(e.g. costs, temperature, distances, amounts)*Can you estimate the number of students in our class without counting?*

- Ask students whether they have helped plan a party before. Potential discussion questions include:
*How many people were invited to the party?**What type of food was served at the party?**How much food do you estimate was needed for the party?*(e.g.,*Can you estimate how many slices of pizza were needed for all the party guests?*)

- Read
*Moira’s Birthday*to the class.

Activity:

- After reading the story, inform students that they will be helping Moira plan a new birthday party.
- Students will work through different scenarios to help Moira plan her party. Present the slideshow (Appendix A) and read the scenario on the first slide.
- Suggest to students that they think about their answers before sharing, but should take too much time because the objective is to quickly estimate quantities.
- Read the “speaker notes” underneath the slides for potential responses.

- Work through the scenarios on each of the slides using the same procedure.

Conclusion:

- Discuss the various strategies that students used to estimate quantities. Ask students to share their new understandings of estimation as a tool for planning.

- Are students able to quickly estimate quantities in real-life scenarios?
- Are students able to round whole numbers to the nearest ten or hundred?
- Do students justify their estimations using the real-life context of scenarios?

- Ask students to create their own party scenarios and estimate the number of items required for each scenario.
- Challenge students to estimate the number of pizzas required for a class party.

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