Сложение натуральных чисел. Свойства сложения

object(ArrayObject)#862 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(119) "Сложение натуральных чисел. Свойства сложения. ( обобщающий урок)"
    ["seo_title"] => string(76) "slozhieniie_natural_nykh_chisiel_svoistva_slozhieniia_obobshchaiushchii_urok"
    ["file_id"] => string(6) "426600"
    ["category_seo"] => string(10) "matematika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1503981928"
  }
}

object(ArrayObject)#884 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(53) "Вычитание натуральных чисел "
    ["seo_title"] => string(32) "vychitaniie-natural-nykh-chisiel"
    ["file_id"] => string(6) "111506"
    ["category_seo"] => string(10) "matematika"
    ["subcategory_seo"] => string(11) "presentacii"
    ["date"] => string(10) "1407565435"
  }
}

object(ArrayObject)#862 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(163) "Урок-игра "Счастливый случай" по теме "Сложение, вычитание и умножение натуральных чисел" "
    ["seo_title"] => string(100) "urok-ighra-schastlivyi-sluchai-po-tiemie-slozhieniie-vychitaniie-i-umnozhieniie-natural-nykh-chisiel"
    ["file_id"] => string(6) "157150"
    ["category_seo"] => string(10) "matematika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1421561913"
  }
}

object(ArrayObject)#884 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(80) "Вычитание натуральных чисел и его свойства "
    ["seo_title"] => string(49) "vychitaniie-natural-nykh-chisiel-i-iegho-svoistva"
    ["file_id"] => string(6) "237080"
    ["category_seo"] => string(10) "matematika"
    ["subcategory_seo"] => string(11) "presentacii"
    ["date"] => string(10) "1444230050"
  }
}

object(ArrayObject)#862 (1) {
  ["storage":"ArrayObject":private] => array(6) {
    ["title"] => string(50) "Сложение натуральных чисел"
    ["seo_title"] => string(29) "slozhieniienaturalnykhchisiel"
    ["file_id"] => string(6) "312655"
    ["category_seo"] => string(10) "matematika"
    ["subcategory_seo"] => string(5) "uroki"
    ["date"] => string(10) "1459362307"
  }
}