March 2022 - Down River Resources | Your Elementary Math Guide
Have you noticed that learning teen numbers is difficult for students? There are good reasons teen numbers are so difficult! Teen numbers do not follow the typical number naming system in English. As a result, teen numbers have been dubbed "tricky teens" by teachers of yesteryear. Eleven, twelve, and thirteen are, by far, the most difficult teen numbers to master. Find out the reasons why teen numbers are tricky and read about how you can help your young mathematicians learn teen numbers with ease.

Tricky Teens are Hard for Kindergarten and First Grade Students

Here's just a few reasons why learning teen numbers in kindergarten and first grades is so challenging for young mathematicians.

1. Teen numbers are an anomaly. Their digits are not written in the order of other two-digit numbers.

The word structure does not correlate with the numerical parts. 

In contrast, in some East Asian languages, the word for 18, for example, translates into "ten eight," and 38 translates into "three ten, eight."  
In the English system, teen and two-digit numbers look like two single-digit numbers written beside each other; nothing shows the 10 value for the number on the left. Young mathematicians need verbal and visual supports for understanding these number words and written numbers.


2. Young mathematicians may have some difficulty with transitions, such as through the teen numbers and between decades.

Often times, young mathematicians say something like “twoteen” for “twelve” or “oneteen” for “eleven”. Such mistakes are attributable to the nature of the English teen-number words, which look, for example, like 10 and 1 or 10 and 2 but do not follow that pattern when spoken. 

Young mathematicians often have less difficulty with numbers beyond 20, but can still struggle through the transitions between decades. For instance, the transition between 19 and 20, 29 and 30, and so forth. 

3. The written position of the numerals are the reverse of the oral representation. 

The written position of the numerals and the oral representation of the teen numbers do not match, which causes quite the confusion for young mathematicians. 

For example, if asked to write 17, they might write the 7 first and then put the digit 1 to the left of the 7. They write the correct numerals, but they give evidence of having difficulty in matching the sound of the number with its appearance (the word “seventeen” begins with the word and sound of “seven”, so intuitively it might seem to them that the 7 should be written first). Some students will reverse digits. For example, when identifying two-digit numbers, they will write 37 as 73. 

4. The names of the teen numbers do not correspond with their values.

When young mathematicians hear thirteen, it does not elicit them to think "1 ten, 3 ones." The teen numbers represent a particular challenge for English language learners because the difference between thirteen and thirty is not easy to hear. 

One common misconception is that teen numbers relates more to place value. Learning the numbers 11 to 19 is more about composing and decomposing numbers. 

Young mathematicians need to learn that teen numbers are composed of one group of 10 and some more, or loose, ones. 

Here's three simple ways to help your mathematicians learn teen numbers:

1. Use mathematical language interchangeably. 

When working with teen and two-digit numbers, we say 13 as "thirteen" and as "1 ten, 3 ones" and say 38 as "thirty-eight" and as "3 tens, 8 ones." 

This is especially important for teen numbers as they are exceptions to the patterns for number words. These linked words are used interchangeably and help reinforce the composition of the numbers. 

2. Provide visuals of teen numbers in both written and numeral forms and give a visual cue.

Scaffold the lesson for young mathematicians by providing them with visuals of the teen numbers in both written form and the numeral form. 

Mathematicians also need practice hearing (stress the teen of the number by putting a finger near the mouth) and saying thirteen and fourteen so that they can hear the stress on the teen part of the number.

3. Use Hiding Zero cards. 

Our visual supports for these written numbers include cards that show the decade number, or 10, and cards that are half as wide that show the single digits 1 through 9. 

The single-digit cards fit on top of the 0 on the decade-number cards to enable children to build numbers in such a way that they can still see both parts of the number they are making by flipping up the single-digit card.

Are you looking for more support for your young mathematicians mastering teen numbers?

You might be interested in using these research-based teen number toolkit that contains 10 lesson ideas, activities, printables, and much more!

The Teen Number Toolkit contains lots of printables that facilitators can use during guided math, math intervention, or tutoring. The large cards can be used for whole group lessons too!

The research-based lesson ideas from the Teen Number Toolkit can be used for guided math, math intervention, or tutoring. The Hiding Zero cards are included that were featured in this post too! 

The printable pages from the Teen Number Toolkit can be used for independent practice, in math centers or math stations, or sent home as practice. 

This post on teen numbers focuses on following standards:

TEKS K.2B Read, write, and represent whole numbers from 0 to at least 20 with and without objects or pictures. 

→ TEKS 1.2B Use concrete and pictorial models to compose and decompose numbers up to 120 in more than one way as so many hundreds, so many tens, and so many ones;

→ CCSS K.NBT.A.1 Compose and decompose numbers from 11 to 19 into ten ones and some further ones, e.g., by using objects or drawings, and record each composition or decomposition by a
drawing or equation (such as 18 = 10 + 8); understand that these numbers are composed
of ten ones and one, two, three, four, five, six, seven, eight, or nine ones.

I hope this post inspires you to help your young mathematics learn teen numbers with ease!

What has helped your mathematicians learn teen numbers?

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