第 1 單元，第 1 課
What Is Science?什麼是科學
這課一眼看
The goals of science科學的目標
- science科學: An organized method for collecting and making sense of evidence about the natural world.
- biology生物學: The scientific study of life.
- observation觀察: Noticing and describing events or processes carefully.
- quantitative定量的、量化的: Involving numbers, such as counts or measurements.
- qualitative定性的、質性的: Describing qualities that are not easily counted.
- inference推論: A reasoned conclusion that combines observations with prior knowledge.
Scientific methodology科學方法
- hypothesis假說: A testable possible explanation for a scientific question.
- prediction預測: A statement of what should happen in a test if a hypothesis is correct.
- controlled experiment控制實驗: An experiment that alters a single factor and holds the rest steady.
- independent variable操縱變因、自變項: The one factor a scientist alters on purpose in an experiment.
- dependent variable應變變因、依變項: The factor a scientist measures to look for a response.
- controlled variables控制變因: Factors kept the same in all groups of an experiment.
- experimental group實驗組: The group that receives the changed condition.
- control group對照組: The group kept under normal conditions for comparison.
- data數據、資料: Information gathered during an investigation.
Scientific reasoning科學推理
- inductive reasoning歸納推理: Reasoning from many specific observations to a general conclusion.
- deductive reasoning演繹推理: Reasoning from a general principle to a specific prediction.
- descriptive science描述性科學: Science that explores, observes, and describes nature.
- hypothesis-based science假說導向的科學: Science that begins with a question and a testable explanation.
1The goals of science科學的目標
AWhat science is科學是什麼
- Science is an organized method for collecting evidence about the natural world and making sense of it. It is also the body of knowledge that this process has produced so far. Biology is the branch of science that studies life, from the chemistry inside a single cell to the way whole forests change over centuries.科學是一套有組織地蒐集並分析自然界證據的方法，也是這個過程到目前為止累積的知識。生物學是研究生命的科學分支，範圍從單一細胞裡的化學反應，到整片森林幾百年來的變化。
- Science works toward three aims. It tries to explain why things happen in nature, it looks for the patterns that those explanations reveal, and it uses what it has learned to predict what will happen next. A scientist who studies why some frogs survive a dry season, for example, may then predict which frog populations are at risk when rainfall drops.科學朝三個方向努力：說明自然界的事為什麼會發生、找出這些說明背後的規律，再用學到的東西預測接下來會發生什麼。例如，研究為什麼有些青蛙能撐過乾季的科學家，之後可以預測雨量減少時哪些青蛙族群會有危險。
- Science studies the natural world and nothing beyond it. Any explanation it offers has to be open to testing, using evidence that someone else could examine for themselves. Questions about beauty, right and wrong, or the supernatural cannot be tested this way, so they are outside the limits of science.科學研究的是自然界，不處理自然界以外的事。它提出的任何解釋都必須能接受檢驗，而且用的證據要讓其他人也能自己查證。關於美醜、對錯或超自然的問題無法用這種方式檢驗，所以不在科學的範圍內。
注意
Scientific knowledge is always open to revision. When new evidence does not fit an accepted explanation, scientists change or replace the explanation. This is a strength of science, not a weakness.科學知識永遠可以修正。當新證據和既有的解釋不符時，科學家會修改或取代這個解釋。這是科學的長處，不是弱點。
自我檢查
Which question can science answer: "Does this plant grow faster in red light or blue light?" or "Is red a more beautiful color than blue?" Explain.下列哪個問題是科學可以回答的：「這種植物在紅光下還是藍光下長得比較快？」或「紅色是不是比藍色漂亮？」請說明。
看答案
The first one. Plant growth can be measured and compared, so the question can be tested with evidence. Beauty is a personal judgment that cannot be measured or tested.第一個。植物的生長可以測量和比較，所以能用證據檢驗。美不美是個人的判斷，無法測量或檢驗。
BObservations and inferences觀察與推論
- Science begins with observation: noticing and describing events or processes carefully, using the senses or instruments. Observations can be quantitative, meaning they involve numbers ("the leaf is 6 cm long"), or qualitative, meaning they describe qualities that are hard to count ("the leaf is pale yellow at the edges").科學從觀察開始：用感官或儀器仔細注意並描述現象或過程。觀察可以是定量的，也就是含有數字（「葉子長 6 公分」）；也可以是定性的，描述難以計數的性質（「葉子邊緣是淡黃色」）。
- An inference is a reasoned conclusion that combines what you have observed with what you already know. Seeing chewed leaves and small dark pellets on a plant is an observation; concluding that caterpillars have been feeding on it is an inference. An inference can be wrong even when the observations are correct, so scientists treat inferences as ideas to check.推論是把觀察到的事實和已經知道的知識結合起來，經過推理得出的結論。看到植物上有被咬過的葉子和黑色小顆粒是觀察；判斷有毛毛蟲在吃這株植物則是推論。即使觀察正確，推論也可能錯，所以科學家把推論當作需要再檢查的想法。
Observation or inference?觀察還是推論？
| Statement敘述 | Type類型 | Why原因 |
|---|---|---|
| The mushroom cap is 8 cm wide.蕈傘寬 8 公分。 | Quantitative observation定量觀察 | A measured number有測量的數字 |
| The mushroom smells earthy.蕈菇聞起來有泥土味。 | Qualitative observation定性觀察 | Describes a quality, no number描述性質，沒有數字 |
| Three ants are carrying seeds into a hole.有三隻螞蟻把種子搬進洞裡。 | Quantitative observation定量觀察 | A count of what is seen對看到的東西計數 |
| The ants are storing food for winter.螞蟻在儲存過冬的食物。 | Inference推論 | An interpretation of their purpose對牠們目的的解讀 |
| The lake water looks green and murky.湖水看起來又綠又混濁。 | Qualitative observation定性觀察 | Describes color and clarity描述顏色和透明度 |
| Algae are growing quickly in the lake.湖裡的藻類正在快速生長。 | Inference推論 | An explanation of the green color對綠色的解釋 |
自我檢查
A student writes: "The pond water has 14 small swimming organisms per drop, and they are probably looking for food." Which part is an observation and which part is an inference?一位學生寫道：「池塘水每一滴裡有 14 隻會游的小生物，牠們大概在找食物。」哪一部分是觀察？哪一部分是推論？
看答案
"14 small swimming organisms per drop" is a quantitative observation. "They are probably looking for food" is an inference, because the student cannot directly see what the organisms are trying to do.「每一滴裡有 14 隻會游的小生物」是定量觀察。「牠們大概在找食物」是推論，因為學生無法直接看到這些生物想做什麼。
2Scientific methodology科學方法
AQuestions and hypotheses提出問題與假說
- Investigations usually start when an observation raises a question. A useful scientific question is narrow enough to investigate, such as "Does water temperature change how many brine shrimp eggs hatch in two days?"研究通常從一個觀察引出的問題開始。有用的科學問題要夠明確、能實際研究，例如「水溫會不會改變豐年蝦卵在兩天內的孵化數量？」
- A hypothesis is a possible explanation or answer to a scientific question. It must be testable, and it must be possible for evidence to show it is wrong. A hypothesis is often followed by a prediction, a statement of what should happen in a test if the hypothesis is correct. Predictions are often written as "If … then …" statements.假說是對科學問題提出的可能解釋或答案。它必須可以檢驗，而且必須有可能被證據證明是錯的。假說後面常接著一個預測，說明如果假說正確，實驗中應該會發生什麼。預測常寫成「如果……那麼……」的句型。
From question to prediction從問題到預測
| Step步驟 | Example例子 |
|---|---|
| Observation觀察 | Brine shrimp eggs left in a warm room seemed to hatch sooner.放在溫暖房間的豐年蝦卵似乎比較早孵化。 |
| Question問題 | Does water temperature affect how many eggs hatch in two days?水溫會不會影響兩天內孵化的卵數？ |
| Hypothesis假說 | Warmer water increases hatching because development speeds up.水溫較高會增加孵化數，因為發育速度加快。 |
| Prediction預測 | If eggs are kept at 28 °C, then more will hatch in two days than at 20 °C.如果卵放在 28 °C，那麼兩天內孵化的數量會比放在 20 °C 多。 |
注意
A hypothesis is not a wild guess. It is based on earlier observations and on what is already known. "Brine shrimp eggs hatch better in warm water because their development speeds up" builds on the known fact that many reactions in living things speed up with temperature.假說不是亂猜，而是根據先前的觀察和已知的知識。「豐年蝦卵在溫水中孵化得比較好，因為發育速度加快」，就是建立在「生物體內許多反應會隨溫度升高而變快」這個已知事實上。
自我檢查
Why is "Invisible spirits make the brine shrimp hatch" not a scientific hypothesis?為什麼「看不見的精靈讓豐年蝦孵化」不是科學假說？
看答案
It cannot be tested. There is no observation or measurement that could show it is wrong, so it is outside science.因為它無法檢驗。沒有任何觀察或測量能證明它是錯的，所以不屬於科學。
BControlled experiments控制實驗
- In a controlled experiment, scientists alter a single factor and hold everything else steady. The factor the scientist chooses to alter on purpose is the independent variable; some books call it the manipulated variable. The factor the scientist watches or measures for a response is the dependent variable, sometimes called the responding variable. Every other factor, held steady in all groups, is one of the controlled variables.在控制實驗中，科學家只更動一個因素，其餘全部維持不變。科學家有意更動的那個因素是操縱變因，有些書稱為自變項；科學家觀察或測量、看它是否出現反應的因素是應變變因，有時稱為依變項；其餘在每一組都維持不變的因素都是控制變因。
- Most experiments compare an experimental group, which receives the changed condition, with a control group, which does not. In the brine shrimp test, cups of eggs might be kept at 20 °C, 25 °C, and 30 °C. The cups at the usual hatching temperature can act as the control. The salt concentration, light, number of eggs, and volume of water must be the same in every cup.大多數實驗會比較兩種組別：接受改變條件的實驗組，以及沒有接受改變的對照組。在豐年蝦的實驗中，可以把裝了蝦卵的杯子分別放在 20 °C、25 °C 和 30 °C。放在平常孵化溫度的那組可以當對照組。每個杯子的鹽度、光照、卵的數量和水量都必須相同。
Variables in the brine shrimp experiment豐年蝦實驗中的變因
| Type of variable變因種類 | Meaning意思 | In this experiment在這個實驗中 |
|---|---|---|
| Independent variable操縱變因 | The one factor the scientist changes科學家刻意改變的那一個因素 | Water temperature水溫 |
| Dependent variable應變變因 | The factor that is measured被測量的因素 | Number of eggs hatched after two days兩天後孵化的卵數 |
| Controlled variables控制變因 | Factors kept the same in every group每一組都保持相同的因素 | Salt concentration, light, number of eggs, volume of water鹽度、光照、卵的數量、水量 |
| Control group對照組 | The group under normal conditions, used for comparison在一般條件下、用來比較的組別 | Cups at the usual hatching temperature放在平常孵化溫度的杯子 |
注意
Each condition should be repeated with several samples. If only one cup is used at each temperature, a single damaged batch of eggs could change the result. Repeated trials and larger samples make results more reliable.每種條件都應該用好幾個樣本重複進行。如果每個溫度只用一杯，只要有一批卵本身有問題，就可能改變結果。重複試驗和較大的樣本能讓結果更可靠。
自我檢查
A student tests whether music helps bean seeds sprout. Pots with music are kept by a sunny window, and pots without music are kept in a dark closet. What is wrong with this design?一位學生想知道音樂能不能幫助豆子發芽。播音樂的盆子放在有陽光的窗邊，沒播音樂的盆子放在陰暗的櫃子裡。這個設計有什麼問題？
看答案
Two variables change at once: music and light. If the music pots sprout faster, the student cannot tell whether the music or the light caused it. Light must be a controlled variable.同時改變了兩個變因：音樂和光線。如果播音樂的盆子發芽比較快，學生無法分辨是音樂還是光線造成的。光線必須是控制變因。
CCollecting and analyzing data蒐集與分析數據
- The information gathered during an investigation is called data. Quantitative data are numbers, such as counts and measurements. Qualitative data are descriptions, such as color changes or behavior. Scientists record data in tables as they collect it, then often organize it in graphs to see patterns.研究過程中蒐集的資訊稱為數據（資料）。定量數據是數字，例如計數和測量值；定性數據是描述，例如顏色變化或行為。科學家一邊蒐集一邊把數據記錄在表格中，之後常整理成圖表來找出規律。
- A line graph is useful when the independent variable is continuous, such as temperature or time. A bar graph is useful for comparing separate groups, such as different species. The independent variable usually goes on the x-axis and the dependent variable on the y-axis.當操縱變因是連續的數值（例如溫度或時間）時，適合用折線圖；要比較彼此分開的組別（例如不同物種）時，適合用長條圖。操縱變因通常放在 x 軸，應變變因放在 y 軸。
Sample data: brine shrimp eggs hatched in two days (100 eggs per cup, 3 cups each; invented for practice)示範數據：兩天內孵化的豐年蝦卵數（每杯 100 顆、每組 3 杯；練習用的自編數據）
| Water temperature水溫 | Cup 1第 1 杯 | Cup 2第 2 杯 | Cup 3第 3 杯 | Mean平均 |
|---|---|---|---|---|
| 20 °C20 °C | 3030 | 3434 | 2929 | 3131 |
| 24 °C24 °C | 5252 | 4949 | 5555 | 5252 |
| 28 °C28 °C | 7878 | 7474 | 7676 | 7676 |
| 32 °C32 °C | 4141 | 3737 | 4242 | 4040 |
- Some questions cannot be tested with a controlled experiment, because the variables cannot be changed or because it would be harmful. In these cases scientists use observational studies: they collect data on large natural groups and look for patterns. Such studies can show that two factors are related, but a relationship alone does not prove that one factor causes the other.有些問題無法用控制實驗檢驗，可能因為變因無法改變，或改變它會造成傷害。這時科學家會做觀察研究：蒐集大量自然群體的數據，再找出規律。這類研究可以顯示兩個因素有關聯，但光有關聯並不能證明其中一個因素造成另一個。
自我檢查
Using the table, describe the pattern between water temperature and the mean number of eggs hatched.根據表格，描述水溫和平均孵化數之間的規律。
看答案
As temperature rises from 20 °C to 28 °C, the mean number hatched increases from 31 to 76. At 32 °C it drops to 40, so hatching is highest near 28 °C and falls at the highest temperature tested.水溫從 20 °C 升到 28 °C 時，平均孵化數從 31 增加到 76；到 32 °C 時降到 40。所以在 28 °C 左右孵化最多，在測試的最高溫時反而下降。
DDrawing conclusions做出結論
- After analyzing data, scientists decide whether the evidence supports or does not support the hypothesis. A hypothesis that is supported is not "proven": a later test might still show a problem with it. A hypothesis that is not supported is still useful, because it tells scientists which explanation to drop.分析數據之後，科學家要判斷證據支持還是不支持假說。被支持的假說並沒有被「證明」，之後的實驗還是可能發現它的問題。不被支持的假說仍然有用，因為它告訴科學家哪個解釋該放棄。
- Conclusions should stay within the data. If brine shrimp were tested only between 20 °C and 32 °C, the results say nothing about 5 °C. Scientists also look for possible errors, such as uneven measuring or too few samples, and they describe these limits honestly.結論不能超出數據的範圍。如果豐年蝦只測試了 20 °C 到 32 °C，結果就無法說明 5 °C 時會怎樣。科學家也會檢查可能的誤差，例如測量不一致或樣本太少，並誠實寫出這些限制。
- Often the results raise new questions or lead to a revised hypothesis, which is then tested again. The process is a cycle rather than a straight line, and other scientists repeat the work to see whether they get the same results.結果常常會引出新的問題，或讓人修正假說，再拿去重新檢驗。這個過程是一個循環，而不是一條直線；其他科學家也會重做實驗，看看能不能得到相同結果。
自我檢查
Hypothesis: "Brine shrimp eggs hatch in greater numbers as water gets warmer." Do the sample brine shrimp data (in the previous section) fully support this hypothesis? Explain.假說：「水越溫暖，豐年蝦卵孵化的數量越多。」前一節的豐年蝦示範數據完全支持這個假說嗎？請說明。
看答案
Only partly. Hatching increased from 20 °C to 28 °C, but it fell at 32 °C. The hypothesis should be revised, for example: hatching increases with temperature up to about 28 °C and then decreases.只有部分支持。20 °C 到 28 °C 孵化數增加，但 32 °C 時下降。假說應該修正，例如：孵化數隨溫度增加，到約 28 °C 後就下降。
3Scientific reasoning科學推理
AInductive and deductive reasoning歸納與演繹推理
- Inductive reasoning moves from many specific observations to a general conclusion. A biologist who examines hundreds of different plants and animals and finds cells in every one may conclude that all living things are made of cells.歸納推理是從許多具體的觀察得出一般性的結論。一位生物學家檢查了數百種動植物，每一種都有細胞，就可能得出「所有生物都由細胞構成」的結論。
- Deductive reasoning moves the other way: it starts from a general principle and uses it to predict a specific result. If all living things are made of cells, and a newly discovered organism is alive, then it should be made of cells. Deductive reasoning is how scientists turn a hypothesis into a prediction they can test.演繹推理方向相反：從一般性的原則出發，用它來預測特定的結果。如果所有生物都由細胞構成，而一種新發現的生物是活的，那麼它應該由細胞構成。科學家就是用演繹推理，把假說轉成可以檢驗的預測。
- Biology uses both kinds of work. Descriptive science (also called discovery science) explores, observes, and describes, for example by cataloging the species in a coral reef; it relies mostly on inductive reasoning. Hypothesis-based science starts with a specific question and a testable explanation; it relies mostly on deductive reasoning. Many studies combine the two.生物學兩種研究方式都會用到。描述性科學（又稱探索性科學）負責探索、觀察和描述，例如記錄一片珊瑚礁裡有哪些物種，主要靠歸納推理。假說導向的科學從一個明確的問題和可檢驗的解釋出發，主要靠演繹推理。很多研究兩者並用。
Two kinds of scientific reasoning兩種科學推理
| Inductive reasoning歸納推理 | Deductive reasoning演繹推理 | |
|---|---|---|
| Direction方向 | Specific observations → general conclusion具體觀察 → 一般結論 | General principle → specific prediction一般原則 → 具體預測 |
| Main use主要用在 | Descriptive science描述性科學 | Hypothesis-based science假說導向的科學 |
| Example例子 | Every fish examined has gills, so fish have gills.檢查過的每條魚都有鰓，所以魚有鰓。 | Fish have gills, so this newly found fish should have gills.魚有鰓，所以這條新發現的魚應該有鰓。 |
自我檢查
A researcher counts bird species on 40 islands and notices that larger islands always have more species. She concludes that island size affects the number of bird species. Which kind of reasoning did she use?一位研究者在 40 座島上統計鳥的種類，發現較大的島鳥種總是比較多。她得出結論：島的大小會影響鳥的種數。她用的是哪一種推理？
看答案
Inductive reasoning, because she moved from many specific observations to a general conclusion. Testing the idea on a new island would use deductive reasoning.歸納推理，因為她是從許多具體觀察得出一般結論。如果拿這個想法去預測一座新的島，就是用演繹推理。
這課的重點字
- science科學
- biology生物學
- observation觀察
- quantitative定量的、量化的
- qualitative定性的、質性的
- inference推論
- hypothesis假說
- prediction預測