The basic calls are the bob and the single. Here is the bob:

45312
54132	"bob" called here
51423
15432
14523
41532
45123
54213
52431
25341
23514
32154

It is probably called a bob because extra dodges are required, and bobs and dodges were once the same thing. Here is a table of the work. Now for the Grandsire Doubles single:

45312
54132	"single" called here
51423
15432
15423
51432
54123
45213
42531
24351
23415
32145

This call gets its name from its use of a single change (only one pair of bells cross while the treble is leading. Here is a table of the work for a single, or this diagram graphically shows the sequence of the work.

Once you have mastered these calls, find out about two more calls.