4th Grade Standard (Review)
4.OA.B.4. Find all the factor pairs for a whole number in the range 1-100. Recognize that a whole number is a multiple of each of its own factors. Determine whether a given whole number in the range 1-100 is a multiple of a given one-digit number. Determine whether a given whole number in the range 1-100 is prime or composite.
Here is a good review of how to find all the factors of a number.
This video is similar to the one above but I like how he shows how to use an arrow to take all the factor pairs and make an organized list. This is similar to how I would teach it in 4th grade. This helps students to make sure they get all the factor pairs.