About the sheets
The rhythms mainly work with 8th notes and quarter notes, so playing the 8ths with a down, up strumming pattern, and the quarter notes with down strums would be a good way to strum these exercises.
Some of the notes and rests may be less familiar to beginners, so you might need to brush up on your note values with this reference sheet: Understanding Notes and Rests in Music Notation – Reference Sheet
The A, D and E chords are used a lot in songs, so this sheet is a good way to practice changing between the chords, as well as working on rhythms.
The ukulele chords can be played by beginners, and more advanced players could substitute the Dsus2 and E7 chords for the full D and E chords if they wish.
If you found these free chord progressions useful for learning or teaching with, please check out my guitar and ukulele ebooks with 100 chord progressions in each: