UNITED STATES
Don’t constrict your vocabulary. Expand it with our glossary.
Teachers, scroll down for a quick list of key resources in our Teachers Toolkit.

Photograph by Ami Vitale, National Geographic
- What does “vulnerable” mean?
- Vulnerable simply describes something capable of being hurt or difficult to defend.
- “Vulnerable” describes the lowest level of the “threatened” category of endangered species. Vulnerable species have populations that have declined between 30% and 50% over 10 years or three generations. Giant pandas, sand tiger sharks, and shoebills are all vulnerable species.
- What does “entitlement” mean?
- In this case, entitlement describes the right to guaranteed benefits under a government program.
- One of the most visible entitlement programs in the U.S. is the National School Lunch Program, which serves more than 5 billion meals every year. (!) Making sure students are receiving the most nutritious and ethically sourced food is a huge issue throughout the country. Learn about the issue and how you can get started making a difference with “Rethinking School Lunch,” a planning framework and the accompanying visual guide.
- In this case, entitlement describes the right to guaranteed benefits under a government program.
- What does “diversity” mean?
- Diversity simply means difference or variety.
- Biodiversity describes all the different living organisms in an area—animals, plants, fungi, algae. Biodiversity can exist in an area as vast as the Amazon rain forest and as tiny as your bellybutton.
- Diversity simply means difference or variety.
- What does “transgender” mean?
- Transgender describes a person whose gender identity does not match their physical sex.
- Use Nat Geo resources to encourage students to engage in thoughtful conversations around gender and identity. Download this outstanding educator guide, and request a screening of our “Gender Revolution” documentary here.
- Transgender describes a person whose gender identity does not match their physical sex.
- What does “fetus” mean?
- Fetus describes a mammal embryo in the later stages of development.
- Some fetuses display rare—weird—characteristics that would make life as a mature animal difficult. Here is a great article on the discovery of a two-headed shark fetus. What challenges do you think a two-headed shark would face in the wild?
- Fetus describes a mammal embryo in the later stages of development.
- What is “evidence-based” research?
- Evidence-based research prioritizes data that can be measured, observed, examined, and analyzed to support a conclusion.
- What is “science-based” research?
- Science-based research prioritizes knowledge based on observation, identification, description, investigation, and explanation.
TEACHERS TOOLKIT
Washington Post: CDC gets list of forbidden words: Fetus, transgender, diversity
Nat Geo: Glossary
Nat Geo: Endangered Species Categories and Criteria
Nat Geo: School Lunch Issue Guide
Nat Geo: What is biodiversity?
Nat Geo: Gender Revolution guide
Nat Geo: National Geographic and the Common Core
Nat Geo: Beyond Yellowstone