Vowel team OO makes two sounds; both are a form of  /oo/.

The more common sound is a longer /oo/, as in “room”.

Sometimes, it can say a short /ů/, as in “book”; however, this sound is not as predictable, depending on the speaker. 

When decoding you can first try the longer /oo/ sound and then as you blend the word as naturally spoken, you can listen if it makes the shorter sound as in “book”.

Look at this image and decide how it can help you to remember the two sounds of vowel team OO.