This level is marked by significant rules changes (baseball, not softball) like 90-foot base pathes, ability to take a pre-pitch lead, and occasional enforcement of the balk rule.
It is also an age where absenteeism and back talk may become a problem.
Here is the additional curriculum for the 13-15 age group:
55. balk rule
56. how to take a primary lead at each base in different situations
57. how to dive back to base
58. pitcher pick-off and fake pick-off moves
59. how to hold a runner on base
60. how to take a secondary lead
61. cut off throw from the outfield
62. two-strike hitting
63. how to draw a balk while on base
64. take advantage of pitcher who uses full-windup with runners on base
65. batter help runner at first regarding pick-off move by left-handed pitcher
66. steal home on the pitch
67. home-plate base coaching by on-deck batter
68. dropped-third-strike offense and defense
69. outfield throw two bases ahead of lead runner on a base hit
70. curveball