does boot has a long u sound?

Dear teachers,

Does "long u" sound come with two variations? I read from the phonics book that words such as "cube," "beautiful" have "long u" sound, which I understand perfectly. "Long u" sound has exactly the same sound as the letter name (u).

What I don't understand is that words such as "boot" "blue" "juice" also are listed as having "long u" sound. Vowels in these words sound a bit different to my ears.

Boot would be /bu:t/, while cube is /kju:b/. So both /u:/ and /ju:/ are "long u" sound?

So, what's going on here?

Thanks!
Harriet

What you have said is correct. What's going on is precisely what you've identified.
Some people might argue that the /j/ is not part of the /u:/, so you'd expect the /u:/ component to sound the same, and it does.

All the words you listed have a long "u" vowel sound for me.