A child sees the numeral 14 and says 'that's just a 1 and a 4 — that's one and four.' What understanding is missing?
AThe child forgot that 14 comes after 13 in the counting sequence
BThe child is treating the two digits as separate numbers instead of understanding they work together as a single number representing fourteen
CThe child cannot recognize what the symbols 1 and 4 look like
DThe child doesn't yet know how to count to ten
Teen numbers use two digits that together represent one quantity — not two separate numbers added together. Fourteen is a single number: one group of ten and four extra ones, written as '14.' Reading each digit in isolation misses the key idea that two-digit numerals encode both a tens value and a ones value in a single written form.
Question 2 Multiple Choice
What makes the numeral 20 different from all the teen numbers (11–19)?
A20 uses three digits instead of two
BThe right digit of 20 is 0, meaning there are no extra ones beyond the two groups of ten
C20 is smaller than all the teen numbers
D20 starts with 2, which means there are 2 ones
20 is the first number where the right digit is 0 — two complete groups of ten with no leftover ones. In all teen numbers, the right digit is 1–9, representing the ones beyond a single group of ten. 20 introduces the idea that a place value can hold zero, and that the left digit can be something other than 1.
Question 3 True / False
In all teen numbers from 11 to 19, the left digit is always 1.
TTrue
FFalse
Answer: True
Yes — every teen number contains exactly one group of ten. The left digit records that group of ten, so it is always 1 for 11 through 19. The right digit (1–9) counts the extra ones beyond that group. This structure is why these numbers are called 'teen numbers' and why they are all written with 1 on the left.
Question 4 True / False
The numbers 11 and 12 are not really teen numbers because their spoken names ('eleven' and 'twelve') do not contain the word 'teen.'
TTrue
FFalse
Answer: False
11 and 12 are definitely teen numbers — they each have a 1 on the left (one group of ten) and a 1 or 2 on the right, exactly like 13–19. Their spoken names don't say 'teen' because of an old irregularity in English, but their mathematical structure is identical to the other teen numbers. The naming is a language quirk, not a mathematical difference.
Question 5 Short Answer
Why are the numbers 11–19 written with TWO digits, while single-digit numbers like 7 only need ONE digit?
Think about your answer, then reveal below.
Model answer: Numbers 11–19 each contain one group of ten plus some extra ones — a quantity greater than 9, which is the largest single digit. A single digit can only represent 0 through 9. Using two digits lets us record both pieces of the number: the left digit (always 1) shows the group of ten, and the right digit shows the extra ones.
This is the core principle of place value: each position in a multi-digit number carries a different value. The teen numbers are the first time students encounter two-digit numerals, so understanding why two digits are needed — because the quantity exceeds what one digit can represent — builds the foundation for all multi-digit number sense.