First graders will learn to identify odd and even numbers, and they will learn what the words "odd" and "even" mean.
In first grade, children are introduced to the concept of even and odd numbers. They will work with small quantities (no more than 20) which can be easily manipulated with counters. In second grade, this area will become more difficult, as children will be expected to identify even and odd based on written numbers up to 100 or higher.
It doesn't seem as if the ability to identify a number as even or odd would be that important a skill for kids to learn. Turns out, it is--not so much for the name odd or even, but more to give kids an introduction to the patterns of objects and numbers. The exact pairing of numbers is an important concept in math and in life, and will be needed over and over again as kids learn skip counting, or in later years when working with such math as division and prime numbers. The names "even" and "odd" simply give kids the vocabulary they will need to talk about these concepts as they work with them.
With some hands-on practice, first graders generally catch on to this concept fairly quickly. In this early stage, their main source of confusion is likely to be adults' awkward attempts to explain odd and even numbers ("It's because you can, um, divide all the even numbers by two...")
The real challenge will happen a bit later, when kids are expected to identify larger numbers as odd or even--the ones that are too big to count. At this point, kids will need to have memorized the 2-4-6-8-0 evens sequence and the 1-3-5-7-9 odds, and use the final digit in the number to identify it. Usually, though, kids don't get into this level until second grade.
Even numbers can be paired up exactly. Odd numbers can't.
If your first graders are zipping through this stuff and want something a bit more challenging, try these:
For more practice with odd and even numbers, take a look at our fun Activities for Even and Odd Numbers.