Standards-based assessment and Instruction

# Science 6-8

### How Is My Breathing Rate Related to My Pulse?

Have you ever raced after someone, trying to catch up? When you finally caught up, you may have felt your heart pounding, and you were probably out of breath. In this investigation, you will use what you've learned about the circulatory and respiratory systems and the purpose of blood to understand the connection between your breathing rate and how fast your heart may be pounding.

Your group will be assigned to a physical activity and work together to collect data on your heart and breathing rates. The task will have these roles: the "timer," the "runner/jumper" and the "pulse keeper." The "pulse keeper" should be the one who can find the pulse the easiest on the other person's wrist. You should practice taking these rates a few times before you begin investigating.

Record your data at rest and after 1 minute of the activity. Then make a table to show your findings. Be sure to include titles for the columns and rows. Next, use your data table to create a double-line graph that shows both rates and what you discovered about the relationship between breathing rate and pulse. Your conclusions should tell whether your prediction was supported by the data.

### Disciplinary Core Idea

• LS1.A Structure and function: All living things are made up of cells. In organisms, cells work together to form tissues and organs that are specialized for particular body functions.

• LS1.A Structure and function: Organisms have both internal and external macroscopic structures that allow for growth, survival, behavior, and reproduction.

### Crosscutting Concepts

• Cause and effect
• Patterns
• Scale, proportion, and quantity
• Stability and change
• Structure and function
• Systems and system models

### Science and Engineering Practices

• Analyzing and Interpreting Data: Construct, analyze, and/or interpret graphical displays of data and/or large data sets to identify linear and nonlinear relationships. Use graphical displays (e.g., maps, charts, graphs, and/or tables) of large data sets to identify temporal and spatial relationships. Analyze and interpret data to provide evidence for phenomena.
• Asking Questions and Defining Problems: Ask questions that can be investigated within the scope of the classroom, outdoor environment, and museums and other public facilities with available resources and, when appropriate, frame a hypothesis based on observations and scientific principles. Ask questions that arise from careful observation of phenomena, models, or unexpected results, to clarify and/or seek additional information. Ask questions to identify and/or clarify evidence and/or the premise(s) of an argument.
• Constructing Explanations and Designing Solutions: Apply scientific ideas, principles, and/or evidence to construct, revise and/or use an explanation for real-world phenomena, examples, or events. Construct an explanation that includes qualitative or quantitative relationships between variables that predict(s) and/or describe(s) phenomena. Construct an explanation using models or representations. Construct a scientific explanation based on valid and reliable evidence obtained from sources (including the students' own experiments) and the assumption that theories and laws that describe the natural world operate today as they did in the past and will continue to do so in the future.
• Developing and Using Models: Develop and/or use a model to predict and/or describe phenomena. Develop and/or use a model to generate data to test ideas about phenomena in natural or designed systems, including those representing inputs and outputs, and those at unobservable scales.
• Obtaining, Evaluating, and Communicating Information: Communicate scientific and/or technical information (e.g. about a proposed object, tool, process, system) in writing and/or through oral presentations.
• Planning and Carrying Out Investigations: Collect data to produce data to serve as the basis for evidence to answer scientific questions or test design solutions under a range of conditions. Plan an investigation individually and collaboratively, and in the design: identify independent and dependent variables and controls, what tools are needed to do the gathering, how measurements will be recorded, and how many data are needed to support a claim.
• Using Mathematics and Computational Thinking: Use mathematical representations to describe and/or support scientific conclusions and design solutions. Apply mathematical concepts and/or processes (such as ratio, rate, percent, basic operations, and simple algebra) to scientific and engineering questions and problems.

### Suggested Materials

I had the following materials available for this activity: jump ropes, stopwatches, a space for physical activity, graph paper and rulers. Students also had recording sheets.

I also suggest access to computers so that students can enter their data and create an electronic graphic representation for the data displays.

## Context

My students had been studying the human body and its systems. We began with the circulatory system and investigated the heart and the purpose of blood. Students had also learned that blood carries certain things that are required by cells, tissue and organs, such as nutrients, hormones, white blood cells and oxygen.

For this science investigation, I integrated a data-collection activity from our Everyday Mathematics curriculum. This allowed students to apply their mathematics knowledge of data collection and data display to our science unit on the human body.

## Instructional Stages

Engagement: Students access prior knowledge and engage with phenomena.

Exploration: Students explore ideas and phenomena using inquiry to clarify their understanding of concepts.

Explanation: Students construct explanations of concepts and phenomena.

Elaboration: Students apply learning to new situations.

After studying the circulatory system, students understand that the blood transfers oxygen to cells for necessary functions. This investigation shows how the circulatory system is related to the respiratory system. Students are able to apply their understanding of this relationship to actually investigating their own body systems. They are also asked to display their data in two different representations.

## How the Students Will Investigate

Students work in groups of two or three. We had a brief discussion about the task to get them thinking about the topic. Recording sheets provided some directions on how they would investigate the question. Each group had a stopwatch and was assigned to either a jump rope or to the stairs. (Other possibilities might include running, doing jumping jacks or engaging in another physical activity.)

Before beginning, students recorded their pulse rates while at rest. After they recorded their pulse rates, they recorded their breathing rate for one minute. (The "timer" keeps track during the same time as the pulse is recorded.) Once students were in their groups, I asked the class to think about how well they were able to record their pulses. Could they record their breathing rate without thinking much about it? If so, then that person might want to be the "runner." Another person, also good at recording, might want to be the "pulse keeper." The third person could be the timer.

Then students went to their designated activity. One student completes the activity while another times it. Then the "timer" keeps the time for one minute, the "pulse keeper" records the pulse and the "runner/jumper" counts breaths. While students are performing the experiment, I monitor the pulse and breathing rates that they are writing down. If the rates seem to be off (e.g., pulse rate of 25, breathing rate of 5), you might have them show you one of their recording sessions, or ask if you could see someone else's pulse/breathing rate.

The students can then switch, so that the first student's breathing rate returns to normal. The second and third students can then complete the activity. Although the breathing rate and pulse may not be recorded at exactly the same time, the results are similar and should not affect the graphing piece of the task.

After recording results in their tables, students should try this experiment at least one more time to ensure their results are accurate. They should then average their results. This might be a good place to break from the first class session.

During the second class, students can create graphs (with titles and keys). The most difficult part of this that I found was the scale of "beats per minute." Have the students look at all of their information to determine the scale of the graph. By using a full piece of graph paper, divided by increments of five, we found our information could fit. You may prefer to have students do two separate graphs, although then the relationship between the two lines may not be as obvious.

Science: After completing this experiment, I found other examples of similar tasks. One variation was to use two separate graphs for pulse rate and breathing rate. Another was to time at more frequent intervals, from rest to two minutes at 30-second intervals. The experiments did not implicitly relate the two counts together but instead were done to show how one could monitor both pulse and breathing rate.

Movement/Music: Students could select different types/tempos of music and predict how moving to each would affect heart and breathing rates. Most baroque music is very relaxing to listen to. It is often included in stress management programs because it can produce a heart rate of approximately 60 beats/minute in the listener. Students could explore the effects of listening to different music tempos and compare them with or rank them related to "at rest" rates. Students could also collect heart-rate and breathing-rate data during a practice session for different sports or movement activities.

Mathematics: Students can construct line graphs of data for different physical activities for the purpose of comparing and ranking. Students could determine and discuss differences in the "average rates" for the class in terms of using the mean, median or mode.

Health: Students can compare their investigation findings to research related to regular exercise, developing cardiovascular endurance and physical fitness.

## Teaching Tips and Guiding Questions

Have all students measure their pulses at rest (in a classroom setting). Finding the pulse rate on the wrist is a bit harder but safer than using the neck. (If students press on both sides of their neck at the same time, they could pass out.) Take some time to teach students how to find their pulses. Explain to them to press lightly with the fingertips (not with their thumbs) on the outer side of the wrist. They can try counting for a full minute and then try a count for 15 seconds, multiplying it by 4, to verify.

Write the class results on the board. Notice that most resting pulse rates can range from 75-100 beats per minute. Athletes tend to have slightly lower rates, due to conditioning. Some students will have a difficult time finding and recording their pulses but may see from the results of their peers that a pulse rate of 20, for example, is impossible! You may suggest that those students either try it again or choose to be the timer in the experiment.

Calculate and write the average pulse rate of the class on the board so that students can refer to it when recording their own data (not to use that information as their data, but to check theirs for accuracy).

While students are working on their hypotheses, elicit information about what they know about both the circulatory and the respiratory systems.

• What does each system do for your body?
• How does that relate to exercise? to fitness training?
• What causes you to have a pulse?
• What connection does the blood have to breathing and the heart?
• How can you determine who will be the "pulse keeper" and "time keeper"?
• What titles should be on your table? (You may need to review with the class what a table should look like or refer to a previous experiment in which they made a table with the class.)
• Using your data, can you explain whether or not your hypothesis was correct?
• Look at your graph. What specific information can you find to back up your conclusion?
• What proof do you have that can help you to now answer the question, "Is my breathing rate related to my pulse?"
• What would happen if you stopped exercising? (This may help them think about a rule to connect breathing rate to pulse.) Encourage students again to think of the function of both the respiratory and circulatory systems.

### Possible Solutions

The student should include a hypothesis, which states whether or not breathing rate is related to pulse. There should be some evidence of prior knowledge (of either the circulatory or respiratory system). The data table includes columns and rows, labels and a title. Data for breathing rate and pulse rate are for at least three time frames. The data are accurately translated from the table and plotted on a graph (with title and accurate scale and labels for the axes of the graph). There should be a key on the graph to distinguish the two lines.

Conclusions accurately compare the breathing rate to the pulse rate and cite evidence from the data collected to support or refute the hypothesis. The student gives a reasonable explanation of how s/he effectively used breathing rate, pulse and a stopwatch to measure these rates.

### Student Anchor Papers and Task-Specific Assessment Notes

Click on a level for student example.
Novice The student's hypothesis is only a one-word answer, "yes." It does not state any prediction or reasoning about breathing rate or pulse rate rising or falling. There is no evidence of knowledge of the circulatory or respiratory systems. Data table and data collection are incomplete. Only two time frames are recorded. The rates appear to be inaccurate, being that the pulse rate at rest is recorded as = 80 and after one minute of exercise, it is only = 30. Some columns and rows have titles. Titles and labels are missing from the graph, although a key is included. The scale and intervals on the graph are inconsistent. Data are plotted incorrectly on the graph. Conclusions do not show evidence of reasoning or conceptual understanding. Neither the circulatory system nor the respiratory system is explained in the conclusion. There is only limited evidence of understanding the relationship between breathing rate and pulse.
Apprentice The student's hypothesis states whether or not breathing rate is related to pulse. The data table includes a title and labels for the columns and rows but does not have data in chronological order (from at rest to three minutes). The table includes data for breathing rate and pulse rate for a minimum of three time frames. Data appear to be accurate and complete. A title and axes labels are not included for the graph. No key is included. The intervals for each axis of the graph are consistent, but the data are not shown correctly on the graph. Conclusions accurately compare the breathing rate to the pulse rate. This student's solution is lacking in detail, in that no specific examples from the data are used to support the conclusions. The student's explanation attempts to show reasoning but is not supported by data collected. The explanation does not show a cause-effect relationship and is not consistent with the available data.
Practitioner The student's hypothesis states whether or not breathing rate is related to pulse and includes some prior knowledge of the circulatory and the respiratory systems. The data table includes columns and rows, labels and a title. The table includes data for breathing rate and pulse rate for at least three time frames, recorded chronologically. Labels for the axes of the graph are accurate (including measurement). The scale for each axis is appropriate for the data collected and is shown correctly on the graph. The data are accurately translated from the table and plotted on the graph. A key is included on the graph to distinguish the two lines. Conclusions accurately compare the breathing rate to the pulse rate. The student clearly cites evidence from the data collected to support or refute the hypothesis. The student gives a reasonable explanation based on available data.
Expert The student's hypothesis (which states whether or not breathing rate is related to pulse) relates the respiratory system to the circulatory system. Examples show evidence of applying prior knowledge. The data table includes columns and rows, labels and a title. The table includes data for breathing rate and pulse rate for three time frames, recorded chronologically. Data appear to be accurate. A title and labels for the axes of the graph are included and accurate (including measurement). The scale for each axis is appropriate for the data collected and is shown correctly on the graph. The data are accurately translated from the table and plotted on the graph. A key is included on the graph to distinguish the two lines. There is clear evidence of scientific reasoning in the conclusion. Conclusions are supported by data. There is evidence of extended thinking, such as what might happen when the person rests three to five minutes. The data trend is correctly identified from the graph and used to support reasoning.

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