How do plants and animals get their scientific names? A Swedish biologist and zoologist named Carl von Linné developed a system of classifying and naming plants and animals that is still in use today. A few stops north of Östermalm on the metro is Stockholm University's campus where you'll find the Naturhistoriska Riksmuseet (Natural History Museum) that he founded in 1739. It's the kind of little factoid that a high school student might want to take back to their friends after a visit to Stockholm.
The stately natural-history museum has moved with the times, installing plenty of interactive exhibits, as well as the Cosmonova IMAX movie theater and planetarium. For 250SEK you and at least two other people can experience the Escape Extinction tour, a one-hour escape room experience that informs and entertains the curious. Of course, there are still the traditional displays of dinosaur bones and fossils, and whole forests’ worth of taxidermied wildlife, marine life and the hardy fauna of the polar regions.
There's a cafe in the museum, but for a bit of tranquility, consider the cafe at nearby Bergianska Trädgården.