Writing Good Lab Reports The Claim-Evidence-Reasoning Cycle

What do all science lab reports have in common? All science teachers expect you to write a scientific explanation for what you observe in the lab, relying on evidence as well as theory to support your claim. Usually called a conclusion, but sometimes this is just one part of the conclusion, depending on if the teacher wants anything else addressed.

What aspects of a lab report may be different depending on the class and teacher? Required parts may include: heading, objective, hypothesis, materials, methods or procedure, analysis types and questions. Format: form vs. open-ended (or anything in between. May vary from lab to lab, course to course, and teacher to teacher. You have to follow your instructions. EVERYTHING ELSE

What is the big deal? It’s the same as writing for English class or Social Studies, isn’t it? SIMILARITIES DIFFERENCES writing well correct punctuation, good grammar and mechanics. the use of proper vocabulary expository Provide context a claim with supporting evidence. no opinion no flowery language or poetic flourishes Use scientific vocabulary direct and concise never use first person pronouns, as your findings are not unique and should be unbiased. It’s not all that different from writing an essay in History or English: thesis = claim, support = evidence, conclusion = reasoning.

WHAT IS A SCIENTIFIC EXPLANATION? A written or oral response to a question that requires you to analyze data and interpret that data with regard to scientific knowledge. Three components: claim, evidence, and reasoning. The three are linked together to create a cohesive explanation.

What is a Claim? A testable statement or conclusion that answers the original question. The simplest part of an explanation Usually the easiest to identify. The answer to the objective or the revision of the hypothesis at the end of a lab.

What is the Evidence? Scientific data that supports the student’s claim. come from any of several sources: an investigation (most common) observations reading material archived data only use data that supports the claim in answer to the original question consider whether or not you have sufficient (as in enough) data. Before you clean up your experiment, you should be sure that you know which data to use and how much data to use to support your claim.

Practice: Is it a Claim, or Is it Evidence? Granite has many small crystals. Granite is an Igneous Rock. Combining vinegar and baking soda creates a chemical reaction. The reaction produced bubbles (a gas). Oil is less dense than water. After mixing, oil floats to the top and water sinks to the bottom. Evidence Claim

What is the Reasoning? justification shows why the data counts as evidence to support the claim includes appropriate scientific principles. Do NOT simply make a general link between the claim and evidence. You want to include the scientific background knowledge that allowed you to make that connection between claim and evidence.

Question: Are any of the liquids the same substance?

Use the rubric to grade the CERs that follow. On the handout so kids can score it themselves.

Sample 2 On the handout so kids can score it themselves.

Sample 3 On the handout so kids can score it themselves.

You try writing a CER: Which is it? A duck or a rabbit? Have kids talk this out and write C-E-R on board. Use different colors for each part.

Who do you think took Ms. C’s lunch? It was a dark and stormy afternoon at our school. Seventh-grade students were returning from lunch. Mr. G sat on his stool with a fresh spaghetti-sauce stain on his shirt, while Ms. S ushered students to their seats. “Mmmmm, what a delicious lunch I just had!” Mr. G exclaimed. “I’m completely stuffed. How was school lunch today?” His students looked at him as if he were crazy. Suddenly, Ms. K knocked at the door. She whispered to Ms. S, “Has anyone seen Ms. C’s lunch? She had spaghetti and meatballs, but it seems to have gone missing.” Ms. S thought for a moment, going back in her memory to think if she had seen anything. She turned to Mr. G and asked, “Mr. G, did you see anything? I think you were in Ms. C’s room just before lunch started.” Mr. G widened his eyes a little and quickly said, “No.” He stood up quickly, knocking his lunch box off of the table. When it hit the floor, a sandwich and an apple rolled out. Mr. G scanned the room, and then asked students, “Does anyone know anything about Ms. C’s missing lunch?” Have kids talk this out and write C-E-R on board. Use different colors for each part. Who do you think took Ms. C’s lunch?

Try some on your own. Choose as many as time permits from the next 7 slides. Some are easier than others, requiring less scientific knowledge.

A group of scientists measured some properties of the water in both Ladybug Pond and Tadpole Pond. Their results are shown in the table below. A species of fish called small-mouth bass prefer dissolved oxygen levels at 5 mg/L, a temperature range of 26 – 31ºC, and a pH of 5.5 – 7. Have kids write this out in pairs or groups, on large paper or white boards. Question: Which pond is a healthier environment for these kinds of fish?

Students are learning about physical and chemical changes Students are learning about physical and chemical changes. Physical changes do not change the identity of the substance. When chemical changes occur, the substance transforms from into a new substance. Red litmus paper changes color in the presence of some materials. Vinegar is tested. Then vinegar is combined with colored sugar and tested with the red litmus paper. Then vinegar is mixed with baking soda and tested with the red litmus paper. Have kids write this out in pairs or groups, on large paper or white boards. Question: What type of change is occurring with the vinegar and baking soda reaction?

In the Pacific Ocean, 500 miles off the west coast of Ecuador, lay the Galapagos Islands. On the islands, there are over a dozen species of small birds called Darwin’s Finches. The different bird species are all basically the same except for their beaks. Each species’ beak is a different size and shape, and each beak is specialized for the type of food that the bird eats. The bigger the beak, the bigger the food. For example, the small-beaked birds eat tiny seeds, while the large-beaked birds eat the larger seeds. Have kids write this out in pairs or groups, on large paper or white boards. Q: What will most likely happen to the finch population if the large seed plants became extinct?

Carlos has two liquids, botanic acid and butanol Carlos has two liquids, botanic acid and butanol. He determines a number of measurements for the two liquids and then mixes them together. After heating and stirring the liquids, they form two separate layers, layer A and layer B. Carlos uses a dropper pipette to take a sample from each layer, and he determines a number of measurements for each. These measurements are displayed on the table below. Have kids write this out in pairs or groups, on large paper or white boards. Question: Did a chemical reaction occur when Carlos mixed Butanic Acid and Butanol?

Each Friday, Julie’s track club runs two miles Each Friday, Julie’s track club runs two miles. The graph shows the amount of time that it takes Julie to run the 2 miles each week over a period of 20 weeks. Have kids write this out individually. Question: What is the relationship between the number of weeks Julie practices and her running time?

The graph shown at the right describes the motion of a car moving from west to east. Have kids write this out individually. Question: What is the car’s motion relative to the starting point at time = 8 minutes?

Sources: http://lizastark.com/portfolio/wp-content/uploads/2011/08/Developing-Scientific-Explanations.pdf http://www.cascience.org/csta/pdf/ConferenceHandouts/2013/Yellenberg_C_E_R%20Writing.pdf http://learningcenter.nsta.org/products/symposia_seminars/NSTA/files/HowDoYouKnowThat--HelpingStudentsWriteAboutClaimsandEvidence_12-12-2012.pdf http://www.am.dodea.edu/lejeune/bms/Lion_Docs/documents/CERWriting.pdf http://www.ncsu.edu/labwrite/lc/lc-selfguide.htm http://www.edutopia.org/blog/science-inquiry-claim-evidence-reasoning-eric-brunsell