Answer:
within the first 20 minutes after leaving class
Explanation:
Ebbinghaus forgetting curve shows the decline within our brains's ability to withhold memory over time. According to my research on this curve, I can say that based on the information provided within the question Raven likely forget about 40 percent of the information she has just learned within the first 20 minutes after leaving class. This can be directly seen in Ebbinghaus forgetting curve that I have attached below, if you look at the 40% mark it will indicate a time period of 20 min before forgetting.
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