In my first grade classroom birthdays are celebrated in a low key manner. I have a traditional gift that I’ve been giving for the past 7 or 8 years, so students have come to expect it. During the first days of a school year I take a picture of each student and then put a few creative digital touches on each picture (usually their name and the age they will be; maybe “Happy Birthday”, etc.) I get these printed as a 4×6 print; slide it into a cheap frame and I have a fairly economical gift that they love.
Each teacher in our school has their own birthday traditions. Often they may hang a birthday banner on the wall. Some have a special birthday hat that the celebrated student may wear that day. Gifts are kept small–often a balloon or candy bar. Often the celebrated student gets to pick the recess games, be line leader, etc. One year the 5th and 6th grade teacher found “sundae” gobblets at thrift stores and made each child a candy “sundae” for their birthday. Toward the end of year when everyone had their gobblets they brought them to school and had ice cream sundaes for a treat.
If birthday parties or treats happen, it is up to parents to provide them but it is not required. Usually treats are kept simple such as drink, cupcake, and salties; ice cream bars; or soft pretzels. Once in a while a mom will provide lunch for the class. We do request that the teachers are given prior notice so they can plan their schedules and usually suggest they make it for a break time or the last 15 minutes of the day.
If a child has a Friday birthday, it has become a tradition for the whole school to sing “Happy Birthday” to that child at the end of our Friday morning whole school chapel. Some students are happy their birthday is not on a Friday while others are disappointed theirs is not.
As far as numbers go; it would likely look the same for a small class as for the larger class. (The larger classes may have more opportunities for parties but who is counting.)