Science is at least in part an attempt to explain how the world works. As students of science it is important to learn how to write scientific explanations. Simple scientific explanations are the first step in building theories that model how the real world works.

Scientists collect information about the world and using what they know they try to explain how things work. Or, if they can, why they work the way they do. Using what you learn in science class you can learn to write correct scientific explanations. Given a situation to explain you use a three-step process to write a good explanation. First, you make a claim about the situation that you think is true. Next, you provide one or more pieces of evidence that can be used to support your claim. Finally, you show the reasoning that connects your claim with the evidence. In other words, you clarify the connection between your claim and the evidence.

Step One: Making a Claim

• A claim is a statement of your understanding or belief about a phenomenon or a set of data. A claim can either be a logical conclusion or an educated guess called a hypothesis.
  
  
• When you make a claim you are trying to describe some facts about the world. This can be done by creating a model of how something works. Your claim may also be part of a larger theory.
  
  
• A claim must be a complete sentence (and may be more than one sentence).

Step Two: Provide Evidence

• Evidence can be drawn from work you did in the lab, from observations you made, from the research of others, background information, or prior knowledge.
  
  
• Explanations that use more than one piece of evidence are better than those that only use one.
  
  
• Evidence should be clearly related to the claim being made.
  
  
• Listing the data is not enough. Converting a chart or table into narrative form is not enough to provide evidence. You must interpret data and make it clear how numerical data or other information relate to the claim.
  
  

Step Three: Provide Reasoning

• Good reasoning shows how a scientific principle connects your evidence to your claim.
  
  
• Restate your claim(s) and clearly connect the observations, data and interpretations of both to the claim.
  
  
• Reasoning is the bridge between your claim and the evidence for it. Reasoning that draws on scientific principles makes the relationship between a claim and its evidence clear.