Summarize this article in one sentence.
"  Learning to count by twos, fives, and tens to 100 will improve your child's understanding of number relationships and begin to provide easy reference points. "  "Doubles" are math facts such as "3 + 3 = 6" or "8 + 8 = 16."  Again, these facts provide easy reference points as students learn to add.  A child who knows instinctively that "8 + 8 = 16," for example, can more easily figure out the sum of "8 + 9" by simply adding one to the total. Try grouping cards by fact families to emphasize the relationships among these numbers.  While students should recognize how numbers interact with each other, rote memorization of basic math facts will provide a complementary foundation for moving on to more complicated arithmetic.

Summary:
Instruct children in "skip counting. Encourage children to memorize "doubles. Use flash cards to stimulate memorization.