Lots of children do this, thinking they can gain enough meaning from the rest of the words. And sometimes they can. But usually this is a sign of a struggling reader.
Your daughter needs to learn strategies to figure out new words.
When she reads aloud to you and encounters a word she skips, stop her and cover parts of the word to help her figure it out in small chunks. For example, in a word like “imitate,” cover over all but the “im” part. Ask her to pronounce “im.” Then ask her what a short i sounds like. Show her the “i” in the middle of the word and ask her to put those sounds together. Then show her the “tate” which should be easy to pronounce. Now reveal the word bit by bit as the child says it. You say it too to be sure she hears it pronounced correctly.
But she still might not know what the word means. Help her to understand it. Use it in a couple of sentences. My experience working with children is that many times they can remember the meaning of words, but they cannot use them properly in sentences. Ask her to create her own sentence using the word.
I would make a list of words she has learned this way, and later in the day or the next day, go back to them. Ask her to read the words and tell you what they mean. Return to these words from time to time to reinforce them.
I would also try to find ways to use the words in your everyday conversations with your daughter.
Perhaps your daughter needs more phonics education. You could quickly go over CVC rules of adding suffixes. You could instruct her about prefixes and what they mean and rules for adding them to root words.
Letting your child slide over long, unfamiliar words sets up a bad habit. Eventually, when she gets into middle school classes, she’ll encounter such words routinely and will need strategies to figure them out. Talk to her teacher about the situation. Perhaps there is a reading specialist in your school who could come to her classroom from time to time and help the students decode longer words.
And I will provide more information about how to decode longer words in upcoming blogs. Keep tuned.