Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair practising incubating with a snowball. Atka Bay, Antarctica. May.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) pair practising incubating with a snowball. Atka Bay, Antarctica. May. Winner of the Polar Passion Category of the Nature's Best Photography Competition 2019.

Ingo Arndt / Baya weaver (Ploceus philippinus) subadult birds practising building 'play nest', Singapore.

Andy Rouse / Young Cheetah (Acinonyx jubatus) learning how to hunt Thomson's gazelle fawn (Eudorcas thomsoni) Masai Mara National Reserve, Kenya

Andy Rouse / Cheetah (Acinonyx jubatus) young siblings learning how to hunt Thomson's gazelle fawn (Eudorcas thomsoni) mother cheetah in background, Masai Mara National Reserve, Kenya

Andy Rouse / Cheetah (Acinonyx jubatus) young siblings learning how to hunt Thomson's gazelle fawn (Eudorcas thomsoni) Masai Mara National Reserve, Kenya

Andy Rouse / Cheetah (Acinonyx jubatus) chasing Thomson's gazelle fawn (Eudorcas thomsoni) Masai Mara National Reserve, Kenya

Andy Rouse / Cheetah (Acinonyx jubatus) young siblings learning how to hunt Thomson's gazelle fawn (Eudorcas thomsoni) Masai Mara National Reserve, Kenya

Sergio Hanquet / Divers learning to freedive with sled, more divers at surface. Tenerife, Canary Islands. 2015.

Sergio Hanquet / Person holding on to rope, practising freediving, boat and more divers at surface. Tenerife, Canary Islands. 2015.

Sergio Hanquet / People learning to freedive in Atlantic Ocean. Tenerife, Canary Islands. 2015.

Sergio Hanquet / People learning to freedive in Atlantic Ocean, Tenerife, Canary Islands. 2015.