Look at the picture.
  This bag has 10 balls inside.

  When we skip count by 10s, we don’t count each ball one by one.
  Instead, we jump by 10 every time we see a bag like this.

  Say 10

These two bags have 10 balls each.
  We skip count by 10s — that means we jump by 10 for each bag.

  Say 10, 20

These three bags have 10 balls each.
  We skip count by 10s — that means we jump by 10 for each bag.

  Say 10, 20, 30

These four bags have 10 balls each.
  We skip count by 10s — that means we jump by 10 for each bag.

  Say 10, 20, 30, 40

These five bags have 10 balls each.
  We skip count by 10s —jump by 10 for each bag.

  Say 10, 20, 30, 40, 50

These six bags have 10 balls each.
  We skip count by 10s — jump by 10 for each bag.

  Say 10, 20, 30, 40, 50, 60

These seven bags have 10 balls each.
  We skip count by 10s — jump by 10 for each bag.

  Say 10, 20, 30, 40, 50, 60, 70

These eight bags have 10 balls each.
  We skip count by 10s — jump by 10 for each bag.

  Say 10, 20, 30, 40, 50, 60, 70, 80

These nine bags have 10 balls each.
  We skip count by 10s — jump by 10 for each bag.

  Say 10, 20, 30, 40, 50, 60, 70, 80, 90

These ten bags have 10 balls each.
  We skip count by 10s — jump by 10 for each bag.

Say 10, 20, 30, 40, 50, 60, 70, 80, 90, 100