# 2.NBT.A.2*

Count within 1000; skip-count by 5s, 10s, and 100s.

*TNCore Focus Standard

## Summary:

This particular standard expands on students’ prior knowledge of basic counting skills. Students should recognize, read, and write numerals within 1000, as well as count on in a variety of sequencing patterns anywhere in the range of numbers from 1 to 1000. Students should be able to count on by 5s, 10s, and 100s. One motivation for this standard is that students will be able to develop stategies for addiiton and subtraction. For example, a student who wants to add 784 + 58 can start at 784 and count five tens: 794, 804, 814, 824, 834. Then add eight ones: 835, 836, 837, ...., 842. This technique can also be helpful in determining a missing addend.  Suppose we want to solve the equation 479 + ? = 520. We can do this by counting up from 479 until we get close to 520: 489, 499, 509, 519. So far we have counted up by 10 four times. Counting up by one then produces 520, so we have added four tens + one = 41.

## Understanding the Standard:

• Provide students with opportunities to count by ones, and then to skip-count by more difficult intervals (by 5, 10, 100), starting at any number less than 1000.
• Provide students with opportunities to understand and practice skip-counting by using base-ten blocks to illustrate the process of adding tens. .
• Provide students with opportunities to regroup numbers into ones, tens and hundreds to aid them in skipcounting..

## Questions to Focus Instruction:

• Can students count on fluently beginning at any whole number less than 1000?
• Can students skip-count fluently beginning at any whole number less than 1000 when given a specific sequencing interval (for example, by 5, 10, or 100)?

## Skills

Prior to: Students can count, recognize and extend sequencing patterns up to 120. Go to 1.NBT.1 to see previous skills in this progression.

At Grade Level: Students will be expected to count in a variety of sequences to 1,000. They will recognize and read the word name and digit form of these numbers as well as model them with concrete objects, such as base 10 models.

Moving Beyond:
Mastery of this skill is further demonstrated in a student’s ability to fluently perform all four operations with numbers. This standard helps students to find additional strategies for addition and subtraction through the development of their skip-counting skills from any number.