Operation method:A Teens Board, showing the numerals '10' through '19'. Two boxes consists of lids and numeral 10 printed on nine of the number slots, and 9 wooden tablets where the numerals 1-9 printed on them. Two Tens Board, showing the numerals '10' through '99'. Two boxes consists of lids and numeral 10-40 printed on one box and 50-90 printed on the second box. The boxes consists of nine movable wooden tablets numbered 1-9. Purposes:1.Correct understanding of 11-19 and11-99 for several. 2.Help children grasp the arrangement of several consecutive experience the several sequential relationship. 3.Understand the relationship between the ten-digit, understand the amount and represents the number of symbols.