My university Maths lecturer will be very proud of me for remembering how she stressed the importance of counting. She once told us how she counted her footsteps as she walked, counted the stairs she was climbing, counted in traffic, in the shower, counted, counted, counted....and I thought to myself at the time: "Hey, I do that too!" (And I still do!)
The more time I spend with children who battle with Maths concepts the more I realise how important this seemingly "simple" activity is. To have a concept of the order of numbers when counting forwards and backwards is vitally important to success in Maths.
Once very young children have come to grips with counting from 0-10 and can "hear" the pattern, it is easy for them to grasp counting on from 20, 30, 40, etc as the pattern stays the same. (The early "teen" numbers are, of course, a little trickier to learn as the auditory pattern is not quite the same, but from fourteen to nineteen is a little easier!)
Once children are at school it is not just hearing and saying numbers that is important...seeing them and being able to "read" what they see and order numbers from smallest to biggest and vice versa becomes important. To begin with counting numbers are ordered. As their understanding progresses children become able to order non-consecutive numbers and compare the values of these numbers. To do this they must have an understanding of the numerosity of numbers and be able to count on and back from any number! Counting, counting, counting!
If you wish to practice counting in your classroom, I have just posted a Halloween themed Math Center Activity to both my TpT and TNB stores. "Spooky Cookie Counting" has activities and worksheets included to practice all the counting skills mentioned above.