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.
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.
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.