Learn It
We are all doers of math
Before any new mathematics, the book asks a different question: where does math already live in your day?
Picture itSee what the math looks like before you read about it
Watch me solve itI do — read one step at a time
- The Ferris wheel has 20 cars, and about 4 people fit in each car. About how many people can ride at one time?
- I count the cars: 20. Then I how many riders fit in one car: about 4.
- I do not count every person — an is a reasoned answer that is close enough to be useful.
- 20 × 4 = 80, so I would say “about 80 people.”20 × 4 = 80
Watch out — mistakes students make here
- The lesson isn't about everyone getting the same score — it's about everyone thinking mathematically.
- The lesson says we do math in different ways, not that everyone must use the same method.
- The lesson says everyone is a doer of math, not just the students who finish fastest.
Try it with meWe do — you answer first, then check
Same steps, new numbers.
- 78.5 = 70 + 8.5
- 78.5 = 78 + 0.5
- 78.5 = 80 − 1.5.78.5 = 80
- Every one of those is the same number wearing different clothes. Find two more.
On your ownYou do — solve this one by yourself
Before you start, remember:
- Name three ways you used math this week outside of school.
- Then tell a classmate one math you already have.
Solve: Which decomposition of 78.5 uses multiplication correctly?
My answer
Stuck? Open one hint at a time.
Hint 1
What is half of 78.5?
Hint 2
Half of 78.5 is 39.25.
Hint 3
Two of those halves rebuild it.
Check my answer
39.25 × 2 = 78.5, so halving and doubling is another way to break the number apart.
Turn & TalkSay it out loud with a partner
The Ferris wheel has 20 cars, and you estimated about 4 riders fit in each car. Why is 20 × 4 an and not an exact count?
Try starting with:
- This is an estimate because ___, not an exact count.Esto es una estimación porque ___, no un conteo exacto.
- 20 × 4 gives about ___ riders.20 × 4 da aproximadamente ___ pasajeros.