Young Children Can Be Taught Basic Natural Selection Tables

Table S1. Closed-ended isolated fact questions for Experiment 1 and Experiment 2 with sample justifications. Experiment 1 Experiment 2 Concept Question Accurate Justification Inaccurate Justification Question Accurate Justification Inaccurate Justification Differential Survival After the weather changed, which group of okapis [long or short necks] got more food? Why? Long necks, because they can reach higher. Long necks, because they had more room. Nowadays, will a wilkie with shorter legs probably be healthy and live for a long time? Why? No, because the berries got higher and they couldn’t reach it. No, because they are older. After the weather changed, which group of passerines [big or small beaks] were less healthy? Why? Small beaks, because they got less food. Small beaks, because there was no sun. Nowadays, will a rudoo with a longer neck probably be healthy and live for a long time? Why? Yes, because the red fruit are up on the top of the trees and it has a long neck. I don’t know. After the weather changed, which group of pilosas [thin or wide trunks] had more babies? Why? Thin trunks, because they are more healthy. Thin trunks, because they just got the babies. Nowadays, will a rudoo with a shorter neck probably be healthy and live for a long time? Why? No, because it had shorter necks so it didn't have enough to eat. No, because it doesn’t have room for the babies to fit in. When these baby hemmies grow up, which one [long or short beak] is more likely to have a baby? Why? Long beak, because they are more healthy. Long beaks, because all the other beaks will have the same beak as it. Nowadays, will a wilkie with longer legs probably have lots of children? Why? Yes, because they’re healthy ‘cause they eat the fruit from the trees. Yes, because the appetite is way better because of the legs. See this okapi with a short neck? If this okapi had a baby, what kind of neck [long or short] would the baby have? Why? Short neck, because usually the mother has the same thing as the baby. Long neck, because they have to eat and they use their long neck. These grown-up wilkies both have shorter legs. If these two wilkies with shorter legs had a child, what kind of legs [longer or shorter] would their child probably have? Why? Shorter legs. Because the wilkie’s parents had shorter legs. Shorter legs. Because it’s just a little child. See this young rudoo. It was born with a longer neck. When this rudoo grows up to be an adult, what kind of neck will it have [longer or shorter]? Note. Italicized information differed depending on the animal species under consideration. Shorter neck. Because it already had a shorter neck when it was born so it should have a shorter neck when it’s older. Longer neck. When that one grows up, it would have to have a long neck to be able to survive. Differential Reproduction Trait Knowledge Table S2. Open-ended questions for Experiment 1 and Experiment 2. Experiment 1 Experiment 2 Pilosas had all different sized trunks a long time ago, but now pilosas only have thin trunks, why do you think that happened? Many hundreds of years ago most of the grown-up pilosas had wider trunks but now most of the grownup pilosas have thinner trunks. How do you think that happened? What happened to pilosas with thin trunks? What happened to pilosas with thinner trunks? Why? What happened next after…? [repeat child’s response to previous question] Why? What happened next after…? [repeat child’s response to previous question] Why? What happened to pilosas with wide trunks? What happened to pilosas with wider trunks? Why? What happened next after…? [repeat child’s response to previous question] Why? What happened next after…? [repeat child’s response to previous question] Why? Hundreds of years after the weather changed, were there any families with thin trunks in the group? Why? Did it take a short time or a long time for pilosas to go from having mostly wider trunks in the past to having mostly thinner trunks now? Why? Hundreds of years after the weather changed, were there any families with wide trunks in the group? Why? Note. Italicized information differed depending on the animal species under consideration. Questions were in fixed order. Table S3. Conceptual checklist of natural selection (NS) understanding with examples of open-ended responses in Experiments 1 and 2. Level Overall Category Checklist Open-ended Response Example 0 No isolated facts Lacks sufficient knowledge of isolated facts1 N/A 1 Isolated facts but Has sufficient knowledge of isolated no NS understanding facts1 but one, or more, of the following are also present: - Misconception - No mention of differential survival advantage - Inaccurate mention of any of the three key conceptual components: differential survival advantage, differential reproduction in one generation, differential reproduction in multiple generations Level 1 response: Misconception2 E: …now pilosas only have thin trunks. Why do you think that happened? P: All the wide trunks became small trunks so they could go into the holes. E: What happened to the pilosas with thin trunks? P: They just stayed the same and they kept eating E: What happened to the pilosas with wide trunks? P: They couldn’t eat for a long time so they just waited until their trunks were small. 2 Foundational NS understanding All of the following are present: - Sufficient knowledge of isolated facts - No misconception - Accurate mention of differential survival advantage Level 2 response: Differential survival, no differential reproduction2 E: …now pilosas only have thin trunks. Why do you think that happened? P: The wide trunks couldn’t fit underground to get the milli bugs as well as the ones with thin trunks so when the weather changed they died out. E: So what happened to the pilosas with thin trunks? P: They survived. E: What happened to the pilosas with wide trunks? P: They died out. 3 NS understanding in one generation All of the following are present: - Sufficient knowledge of isolated facts - No misconception - Accurate mention of differential survival advantage - Accurate mention of differential reproduction in one Level 3 response: Differential survival and differential reproduction3 E …now most of the grown-up rudoos have longer necks. How do you think that happened? P: I don’t know. E: What’s your best guess? P: The ones with the shorter necks all died out because they couldn't reach the fruit and then the ones with the longer necks could reach the fruit and had more babies so there were more ones with longer necks. Level 1 response: No mention of differential survival2 E: …now passerines only have big beaks Why do you think that happened? P: They have small beaks and big beaks and it started to rain and the sun came out. E: What happened to the passerines with big beaks? P: They were scared of the rain. E: What happened to the passerines with small beaks? P: They don’t cry. generation 4 NS understanding in multiple generations All of the following is present: - Sufficient knowledge of isolated facts - No misconception - Accurate mention of differential survival advantage - Accurate mention of differential reproduction in one generation - Accurate mention of differential reproduction in multiple generations E: What happened to the rudoos with longer necks? P: I don’t know. E: What’s your best guess? P: They could reach the fruit so they had more babies so there were more and more and more of them. E: Why? P: Because the fruit was up high and the little ones couldn't reach it, the ones with the short necks couldn’t reach it, and the ones with the longer necks could reach the fruit. Level 4 response: Differential survival and reproduction in multiple generations2 E: …now okapis only have short necks. Why do you think that happened? P: The weather changed and the short neck okapis couldn’t get any of the fruit that they need to live. E: What happened to the okapis with short necks? P: They probably died out. E: What happened to the okapis with long necks? P: They had babies and then these had babies and then they kept on having babies. Level 4 response: Differential survival and reproduction in multiple generations3 E: …now most of the grown-up rudoos have longer necks. How do you think that happened? P: Um, you, these [points to shorter necks in past group] couldn’t really eat a lot, and they died of starvation, and these [points to longer necks in past group] got a lot of, lot of things to eat, and had babies, and these [points to shorter necks in past group] mostly died out of starvation. E: What happened to rudoos with longer necks? P: Mmm, they live. E: And why do they live? P: Bec-c-… because they got enough food t-to eat. E: And so what happened next after they lived? P: …They had children and then died. E: And why is that? P: …because everything dies, and they ha-- they got children because they got a lot of, a lot of things to eat. E: And so what happened next after they had children and then died? P: Um, their children grew up to be grown-up rudoos, and then the same thing happened, like, they got old, they had children, and then they died. And the cycle… Note. E = Experimenter; P = Participant. 1Sufficient knowledge of isolated facts was defined as accurately answering and justifying 4 of 5 closed-ended questions in Experiment 1 and 5 of 6 closed-ended questions in Experiment 2. 2 Full open-ended responses taken from Experiment 1. 3Open-ended responses taken from Experiment 2 (edited for length).