Mathematics activities and materials for teaching and reinforcing number concepts are presented. The activities, which rely primarily on number cards, are divided into the following sections: (1) sets less than ten; (2) the teen numbers; (3) sets and numerals to 100; (4) numeration; and (5) words that represent numbers (e.g., "one=1"). An inventory of number cards needed for the activities is included along with samples of the following number cards: picture cards representing the numbers 1 through 19; picture cards representing sets of ten; expanded numeral cards for teen numbers (e.g., "10+1,""10+2," etc.); and overlay cards for teaching place value up to the thousands place. Des Moines (Iowa) Performance Objective numbers which relate to the activities are listed on the left of each page. (DC)