Benchmark lessons are important tools used to teach students skills they will need throughout the course of their science class. The topics involved are not necessarily curricular such as chemistry or biological concepts, but are nonetheless important for the students. Students need the ability to perform many skills in the science classroom such as measurement, data collection, lab safety and many other things. A student may never be asked on a test, how do you read a thermometer but it is likely that in a lab period they will need the temperature of something and as such will need the skill. By dedicating an entire lesson to these skills the teacher ensures that he or she covers material that the students will need on a weekly basis without having to re-teach it ever time.

Graphing Lesson

Purpose

The purpose for this lesson is to teach the students how to appropriately graph data they have collected during an experiment. Students will learn the reasons for graphing data as well as gain an understanding of variables, both independent and dependant. This knowledge will be invaluable to them as they progress through science courses because graphing techniques are an easy useful way to report data and observations from lab work. Many if not most of the labs the students do throughout the year will require graphing and it is important that this section be seen as a tool for them to better explain their data, rather than a burden that they do not really understand.

NSES

The National Science Education Standards specifically addressed by this lesson are those listed below. This chart was taken from the Science Education Program Standards section and as such is not seen as content, but still required for students to succeed in the science classroom.

Examples of Mathematics that Students Should Know and Use

Grades 5-8

- Represents situations verbally, numerically, graphically, geometrically, or symbolically
- Use estimations
- Identify and use functional relationships
- Develop and use tables, graphs, and rules to describe situations
- Use statistical methods to describe, analyze, evaluate, and make decisions
- Use geometry in problem solving
- Create experimental and theoretical models of situations involving probabilities

By learning to graph correctly students are able to represent the physical situation occurring during an experiment. They will be able to make connections between one variable and another, ideally recognizing a functional relationship. Graphing often times allows students to make estimations if a trend is present. Learning to recognize a trend in a graph will often cue students into what might happen if the experiment continued or if different variable were used. Learning to graph ties directly to these standards and through them, the student is learning to act as a scientist. Graphing requires students to make observations about data relationships and gives them the opportunity to expand those observations into predictions about what might occur.

Lesson

I would start off with a brief inquiry led discussion about why we graph. The goal of this whole class discussion would be to get the students to understand that graphing is a good way to organize lots of information in an easily understandable way. I would also like students to understand that often times graphing can lead us to make predictions about data we do not have. I would start off giving the students this information:

When Billy was 2 years old he was 2.5 feet tall. At age 4 he was 3.5 feet tall. At 6, he was 4 feet, and at 8 he was 4.3 feet tall.

I would then ask is there some better way to organize all this information than these sentences. I would be trying to lead the students towards charts and graphs as effective ways of organization.

I would next ask questions of the students about the relationship between Billy’s age and his height. I would ask does how tall Billy is affect how old he is. The students may need a little tinkering, but hopefully they will realize that his height does not affect his age. However, when I Ask the opposite of the students, does how old Billy is affect his height, hopefully the students will get that it does. I am trying to guide the students to the fact that Billy’s height *depends* on his age and that his age is *independent* of his height.

I will then show the students an empty graph on the board and tell them that the long axis is the independent axis and the tall axis is the dependent axis. (If terms like ‘axis’ are outside of the understanding, others like ‘line’ can be used for now.) If those are the axis names, I will ask the students where we should label Age, and Height. I will also ask questions like Age in what? (years) and height in what? (feet) so that students understand the need for labeling their graphs and that we cannot have some data points in some units and some in another. A good example of this would be to have Billy’s height at 10 days and try to place it on the graph at the 10 spot with the hopes that the students would recognize this flaw.

After the points are labeled on the graph I will ask questions like do we think Billy will be taller or shorter at age 10 and do we think Billy was taller or shorter at age 1. Students should be able to recognize the trend in the graph and be able to pick out where/when taller or shorter points can go. Height and age is a great example to use because it will also show the students to problem with assuming too much. If I ask the students will Billy be taller at age 30 and ask how much taller, they will not be able to give an accurate answer, only that he will be taller. Graphing data can gives clues to trends for estimation, but you cannot get completely accurate predictions unless the data follows a functional relationship, a topic the students will delve into later.

After this whole class discussion, I would break the class into smaller groups of 4-5 students and hand out slips of paper with some related data and a blank graph. The activity sheets would resemble this:

Five students in a class all took the same test. Each spent a different amount of time studying for the test. The results are shown below:

Amanda spent 3 hours studying and got a 85. Brett spent 8 hours studying and got a 98. Lucy spent 5 hours studying and got a 90. John didn’t study and got a 55. Mary spent 1 hour studying and got a 65.

What are the variables in this case?

________________________ depends on ______________________________.

Graph the data on the graph paper provided being sure to label the axis including units and to title the graph.

Assessment

The students will stay in their groups and report to work stations about the room. At each station will be a beaker of cold water on top of a hot plate. In the beaker will be a thermometer and next to the station will be a stop watch. The students will be instructed not to touch the hot plate. The teacher will go around the room turning the hot plates onto low power (must be low so water DOES NOT boil) and as this is done the students will be told to start their stop watches. They will record the temperature from the starting point (room temp is around 25 degrees C) every minute for 10 minutes. They will then be asked to take this data home and create a graph that shows the relationship between time and temperature of water being heated.

This assessment is authentic because it measures how well the students can graph data taken from actual experimental conditions. This is how students will be expected to report their findings in the experiments they do in class and this graphing exercise is very similar to those experiments. By giving different variables and asking students to identify them, the teacher ensures that the students have an understanding of the relationship between the independent and dependant variables. By giving the graph as homework, the teacher ensures that the students have all the time they need to make it as fancy or aesthetically pleasing as they want while still being able to show the data. By having the students transfer their recorded data to a graph they gain the understanding of why a graph is better than a list of numbers: it accurately displays the correlation between two factors in an easy to read way.

## Leave a Reply