Ключевые слова: blackboard, by hand, captive, captivity, cell, chalk, chalkboard, chart, closeup, count, counting, data, day, days, draw, enumerate, exile, figure, keep track, keeping track, line, line chart, lines, many, mark, marking, math, measure, number, numbers, pattern, primitive record keeping, prison, prisoner, record, represent, school, score, simple, spend, stick, strike, stripe, stroke, survey, tally, tally chart, tallying, track, wall,