Idea 1of 23
A letter holds a number
What does a letter mean in math?
Today you'll discover
- why a letter stands in for a number
- how a story becomes n + 3
- what n is once the bag is opened
Think firstA bag of marbles nobody has counted
Which expression shows all of Ava's marbles?
Decide first, then press Next. Find what the letter stands in for.
A bag marked n beside 3 loose cubes, with the line: Ava has a bag of marbles she has not counted, and 3 loose ones. Then labels under the picture, 1 bag: n and 3 loose: plus 3, and the expression n + 3. Then the bag opened to show 9, and 9 + 3 = 12. The last step shows Ben's box of crayons and 6 loose crayons, 16 in all.
See the whole ideathe big idea and the key word, in one place
The big idea
A letter, called a variable, stands for a number you do not know yet.
Easy to get wrongA letter is not short for a word. n is the number of marbles in the bag, not the word marbles.
For exampleSome crayons and 6 more is n + 6. If there are 16 in all, the box holds 10.
Key word
- variable
- a letter, like n or x, that stands for a number
Ready to use it?
- Use a letter for an unknown number in a story.