Until recently, I have always used the terms goal and objective interchangeably as if they were the same. However, I knew that I was committing a curriculum faux pas. For someone who cares deeply about the curriculum, I felt that I had to mentally clarify the fine nuances between these two terms if I was going to elevate my instructional practice. By reading Robert F. Mager’s, Preparing Instructional Objectives, I was able to clarify those subtle differences. Thus, my quest to become proficient at writing clear objectives began.
According to Mager, an objective dictates to the teacher, what is worth teaching. It is a clear statement that describes the instructional outcome (i.e. the expected behavior that successful students should exhibit when they have achieved mastery). Since the learning outcome is directly linked to the quality of the instruction, and the quality of the instruction depends on the clarity of the objective, it behooves teachers to prepare for instruction by starting with clear objectives. 
Mager recommends that an objective must include:
- Performance: states what the learner is able to do
- Conditions: describes terms under which the performance is to occur
- Criterion: states acceptable performance
Normally, I would only indicate the performance in an objective and exclude the conditions and the criteria. For example, I would write: the objective is to construct a line graph. However, using the guidelines from Mager, I revised the objective as follows: Given a data table, students will be able to construct a line graph by writing the title to include both independent and dependent variables; numbering the intervals for both x and y axes; listings the variables and their corresponding units for both the x and y axes; adding a key when applicable; and plotting and connecting the data points without extrapolation, with 100% accuracy when any of these elements are required. In the revised version, I have underscored all the overt behaviors that must be revealed in the body of work provided by the students in order to achieve competency for this objective. No longer will students have to guess what I mean by “to construct.” This organizes students by clearly expressing how the objective must be accomplished. In addition, I have included the condition in which the performance will be assessed, when given a data table. Therefore, students know that I will ask them to construct a line graph only when presented with a data table and not under any other conditions. Also, I have given the criteria for acceptable performance, 100% accuracy. Consequently, students know that in order to receive credit, all overt behaviors must be completed without errors; partial credit will not be given for inconsistent intervals, incomplete titles, etc.
A goal, in contrast, is an abstract statement that explains what teachers expect students to know and understand. Since goals are abstract, they can only be measured using indicator behaviors (i.e. performances or visible behaviors) during formative and summative assessments. In essence, objectives can be used to achieve goals.
A good strategy I have found to write a goal is to start with the following sentence prompts: I want students to understand ___ or I want students to know ___. Things that I want my students to know are big ideas or enduring understandings. These are principles, conceptual themes, and issues in the curriculum. For one goal in my living environment curriculum, I wrote: I want students to understand that proteins (i.e. enzymes, receptors, and antibodies) recognize their target molecules (i.e. substrates, hormones, and antigens) by their complementary shape. I was able to measure the students’ achievement of this goal via two performances or indicator behaviors. When given a symbolic representation of a specific enzyme, receptor, or antigen, students are able to draw a symbolic representation or create a model of the respective target molecule, with 100% accuracy.
By mentally clarifying the nuances between these two terms, I was more equipped to provide improved instruction to my students. My instructional approach improved because now I was armed with foolproof strategies to unravel the hidden performances embedded in a goal. Since I was explicitly stating all acceptable performances (for both goals and objectives), I became more cognizant of creating learning experiences that included these measurable behaviors. This also ensured that I would never forget to teach a critical feature of a lesson or unit because these measurable behaviors were serving as my mental checklist. Along with improving instruction, I also used these strategies to transform my construction of assessments to improve their internal validity. The overt behaviors or performances served as guidelines in the type of questions that I selected or generated for my formative and summative assessments. As a result, my assessments were aligned to their respective instructional approaches and objectives.