In a typical training session two Aikidokas face each other to practice Aikido technique. The person who attacks is called uke and the person who defends using Aikido technique is called nage. Nage employes a throw or pin technique demonstrated by the teacher to defend and the uke recieves the technique or takes a fall.
So far I did not find any specific sequence in which the techniques are taught. In each class we learn few new techniques and practice them. This is the basic training.
Aikido is one martial art which cannot be practiced alone. You need a partner to practice.