Dividing Objects into Equal Groups to Share Fairly
About this lesson
In this 45-minute Grade 3 lesson, children help a group of picky aliens share space cookies, dealing counters onto paper plates until every alien gets the same amount. Along the way they write matching division sentences and decide what to do with leftovers. You'll need about 30 counters or cubes and six paper plates per pair, plus markers and chart paper.
- Grade
- 3
- Subject
- Math
- Time
- 45 min
Objective
Students will apply division strategies to split a set of objects into equal groups, write the matching division sentence, and explain what to do with any leftovers.
Materials
- Counters, linking cubes, or small paper squares (about 30 per pair)
- Paper plates or paper circles cut from scrap paper (6 per pair)
- Markers or crayons
- Chart paper
- Whiteboard and whiteboard markers
- Index cards or half-sheets of paper for exit tickets
Hook
Announce in a dramatic news-reporter voice: 'BREAKING NEWS! A spaceship of very picky aliens has landed on the playground, and they will ONLY eat snacks if every alien gets exactly the same amount. If one alien gets even one extra cookie, they all start crying green slime!' Draw three goofy aliens on the board, show 12 counters as 'space cookies,' and ask students to help you share them fairly before the slime tears begin.
Main Activity
Model the hook problem by dealing the 12 'space cookies' one at a time onto three alien plates until they run out. Then write 12 ÷ 3 = 4 and explain that the first number is the total, the second is the number of groups, and the answer is how many each group gets. In pairs, students draw silly alien faces on their paper plates, then work through a set of 'Alien Snack Orders' written on the board, such as '20 space cookies for 4 aliens,' '18 moon noodles for 6 aliens,' '15 star sprinkles for 5 aliens,' and '24 comet candies for 3 aliens.' For each order, pairs share out the counters, sketch the equal groups, and write the division sentence on their paper. Next, introduce the 'Slime Alert' challenge: '14 cookies for 4 aliens.' Pairs must figure out that each alien gets 3 and 2 cookies are left over. Then they invent a funny solution for the leftovers, such as feeding them to the alien's pet space hamster. End by having a few pairs share an order on the chart paper and act out how happy (or slimy) their aliens were.
Discussion Questions
- How did you know when every alien had a fair share?
- What did you notice about the number of cookies each alien gets when more aliens show up for the same number of cookies?
- How could knowing your multiplication facts help you share the snacks faster?
- When there were leftovers, why couldn't we just give them to one alien? What other fair choices could we make?
- Can you think of a time in real life when you needed to share something equally?
Exit Ticket
On your card, solve this alien emergency: 'There are 21 space cookies and 7 aliens. How many cookies does each alien get?' Draw the equal groups, write the division sentence, and add one sentence explaining how you know it is fair.
Differentiation
Support: Give struggling learners smaller totals (6 to 12 counters) and only 2 or 3 alien plates at first. Encourage them to deal counters one at a time, saying 'one for you, one for you, one for you' out loud. Provide a sentence frame on a card: '___ cookies shared among ___ aliens is ___ each, so ___ ÷ ___ = ___.' Pair them with a supportive partner who handles the counters while they record.
Extension: Advanced learners write their own 'Alien Snack Orders' for classmates, including at least one with leftovers. Then they tackle a two-step challenge: 'The aliens have 30 cookies. 6 aliens share them equally, then each alien gives 2 cookies to their space hamster. How many cookies does each alien have left to eat?' They write a matching multiplication sentence to check each division answer.
