辅助 20以内各数的认数、数数和计算的自制计数器，人们惯用了几十年，其结构是：在一个木架子的中间，上下装两根铁丝，每根铁丝上各串着 10个算珠。笔者通过实践，对此计数器稍作改进，觉得效果更好。改进之处是：只装一根铁丝 (比原来要长些 )，铁丝串上 20个算珠，其中从左 Assisted by the number of recognition within 20, counting and counting of self-made counter, people used to decades, the structure is: in the middle of a wooden shelf, up and down with two wire, each wire on the string of 10 Count beads. The author through practice, a slight improvement on this counter, I feel better. Improvements are: only install a wire (longer than the original), wire string 20 count beads, which from the left