Some things cannot be moved. A door cannot be laid next to a table.
Step 1: Let's Learn
Read it, or press Listen and follow the words.
Use a string
Cut a string the same length as one thing. Then carry the string to the other.
If the door is longer than the string, and the string is longer than the table, then the door is longer than the table.
Why a third object works
If a stick is longer than the desk and shorter than the door, the door is longer than the desk. You compared two things that never met.
The middle thing must not change
Use the same stick both times. A different stick each time proves nothing at all.
Step 2: Try It Yourself
Tap and try it out.
Door
9
String
6
Table
4
Step 3: Watch an Example
One step at a time.
Watch Ben Use a String
Ben wants to know if the door is longer than the table.
- Step 1
He cuts a string as long as the table.
Step 4: Your Turn
Practice makes it stick.
The Bookcase
Problem 1 of 1
A shelf is longer than a string. The string is longer than a book. Is the shelf longer than the book?
Try It Yourself
Set the string between the other two, then check the rule works.
Window
8
String
5
Chair
3
Step 5: Quick Check
Show what you know.
Question 1 of 2
A rope is shorter than a string. The string is shorter than a pole. Is the rope shorter than the pole?
Question 2 of 2
Why use a string instead of moving the door?
What You Learned
- Some things cannot be moved to compare.
- Use a string as a go-between.
- If A beats the string and the string beats B, then A beats B.