At this stage, you have been exposed to most of the rhythmic patterns that you will experience.
As you know, most music is written in Common-Time. You have also learned about Compound-Time and Cut-Time, which covers the most frequent time-signatures that you will perform.
Composers have experimented with re-defining measure patterns and creating additional beat sub-divisions.
Hemiola is a rhythm device that occurs when there are 3 beats in a measure to bring attention to musical cadences. A cadence is a musical arrival point.
Hemiola is a grouping of accented beats that forms a rhythmic flow that is twice as slow as the main beat. (Or half as fast)
The pattern of Three Implied Half-Notes, form the Hemiola above. Measures 2 and 3 above display a half note, a tied quarter-note to a quarter note, (an across the bar line ‘half-note’) and another half-note.
The Hemiola is most often utilized before the end of a composition, large section or phrase.