Collecting Clues Like a Scientist

Today you will learn to collect observations and measurements and use them as evidence. Evidence is the proof you gather to answer a question. Scientists do not just guess. They look, they measure, and they write it all down.

An observation is something you notice with your senses. You have five senses. You can see a red cardinal on a fence. You can hear rain on the roof. You can smell rain on the sidewalk. You can touch rough tree bark. You can taste that a lemon is sour, but only when a teacher says it is safe.

[Visual 1: A circle split into five parts. Seeing: "a red cardinal on a fence." Hearing: "rain on the roof." Smelling: "rain on the sidewalk." Touching: "rough tree bark." Tasting: "a lemon is sour (only when a teacher says it is safe)."]

A measurement is a number you get by using a tool. You measure the length of a leaf with a ruler. You measure the mass of a rock with a balance. Mass is how much stuff is inside something. You measure the temperature of water with a thermometer.

[Visual 2: A tool table with two columns, "What we measure" and "Tool." Row one: "Length of a leaf" and "Ruler." Row two: "Mass of a rock" and "Balance." Row three: "Temperature of water" and "Thermometer."]

One class grew a bean seedling in the window. They asked, "How fast does our bean grow?" They measured it with a ruler. Here is the chart the class kept. Notice that every number has a date next to it.

[Visual 3: A two-column table the student can copy. Column names: "Date" and "Height." Row one: "Monday, March 3" and "4 cm." Row two: "Friday, March 7" and "7 cm."]

Now the class can compare. The bean was 4 cm on Monday. It was 7 cm on Friday. 7 - 4 = 3. The bean grew 3 cm in one week. That is evidence. You can collect evidence in your Texas town, too. You can write down the temperature outside your classroom each morning. Then you can compare hot days and cool days.

[Visual 4: A bar chart with two bars. The bar for "Monday, March 3" reaches 4 cm. The bar for "Friday, March 7" reaches 7 cm.]

Always write your evidence down. Always put the date next to it. Then you can compare it later and see what changed.

Try it: A class kept a chart of birds at their feeder. Monday, 5 birds. Tuesday, 3 birds. Wednesday, 6 birds. What question does this chart answer, and how many more birds came on Wednesday than on Tuesday?

[Visual 5: A two-column table. Column names: "Day" and "Number of birds." Row one: "Monday" and "5." Row two: "Tuesday" and "3." Row three: "Wednesday" and "6."]

Answer: The chart answers the question, "How many birds visit our feeder each day?" Wednesday had 6 birds. Tuesday had 3 birds. 6 - 3 = 3. So 3 more birds came on Wednesday than on Tuesday. The chart is the evidence, because the class wrote down each number with its day.