seegongsik
Grade 5 (age 10-11)

grade 5 Patterns and Correspondence

Patterns and correspondence is about finding how one quantity changes as another changes, and writing that relationship as a formula. If one bottle holds 500 mL, then 2 bottles hold 1000 mL and 3 bottles hold 1500 mL: once you know the number of bottles, the total is fixed. In a table, look at how much △ grows each time ○ goes up by 1, and you can write the rule as a formula such as △ = ○ × 3 + 1. In the first picture you change the multiplier and the number added to see the table and the graph; in the second you change the amount in a bottle to see the total for each number of bottles.

How two quantities are related

🔗 When one is fixed, so is the other
①If one bottle holds 500 mL, 3 bottles hold 500 × 3 = 1500 mL
②Once you know the number of bottles, the total is fixed. A relationship like this, where one quantity changes as another changes, is called a correspondence
③Call the number of bottles ○ and the total △, and the relationship can be written as a single formula, △ = ○ × 500

Making a table

3
1
💡 Finding the rule in a table
①The top row of the table is ○ and the bottom row is the matching △. With the starting values, multiply by 3 and add 1, △ goes 4, 7, 10, 13 and so on
②Each time ○ goes up by 1, △ goes up by the multiplier, 3. That is why the points on the graph lie on a straight line
③Work back to ○ = 0 and you get 4 − 3 = 1, the number added; put together, the rule is △ = ○ × 3 + 1
④The 1 → 4, 2 → 7 and 3 → 10 under the table are what you get by putting ○ into this formula

Correspondence in everyday life

💡 Changing the amount per bottle
①The second picture is a correspondence with multiplication only and nothing added: total = number of bottles × amount per bottle
②With the starting 500 mL, 1 bottle is 500 mL, 2 bottles 1000 mL and 3 bottles 1500 mL, so each extra bottle adds 500 mL
③Change the amount per bottle and every bar stretches or shrinks in the same proportion, so the bar for ○ = 5 is always 5 times as long as the bar for ○ = 1
500 mL

Summary

Correspondence
once ○ is fixed, △ is fixed
A relationship in which one quantity changes as another changes
The rule as a formula
△ = ○ × (multiplier) + (number added)
Seeing how much △ grows when ○ goes up by 1 gives you the multiplier
The rule on a graph
the matching points lie on a straight line
If △ always grows by the same amount, the line through the points is straight
🎯 At a glance
①Correspondence: once one quantity is fixed, the other is fixed too
②A table makes the rule easier to see
③Written as a formula, the rule gives values that are not in the table
④Bottles and total amount, items and price, time and distance: everyday life is full of correspondences
⑤Looking at the table and the graph together makes the rule clearer

Examples and Unit Test

Example 1
One bottle holds 500 mL. How many mL are there in 3 bottles?
1
Once the number of bottles (○) is fixed, the total (△) is fixed: this is a correspondence.
2
Total = bottles × 500, so 3 × 500 = 1500 (mL).
▸ 1500 mL
With the starting setting of the second picture, the bar for ○ = 3 shows 1500 mL.
Example 2
One bottle holds 500 mL. If ○ is the number of bottles and △ is the total, how do you write the correspondence as a formula?
1
Each time ○ goes up by 1, △ goes up by 500.
2
So the formula is △ = ○ × 500.
▸ △ = ○ × 500
When ○ is 0, △ is 0 too, so the formula needs only multiplication, with nothing added.
Unit Test
In △ = ○ × 500, what is △ when ○ = 5?
①505
②2500
③5500
④100
▸ ② 2500
1
Put ○ = 5 into △ = ○ × 500.
2
5 × 500 = 2500.

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