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How Big is Your Heart?

  • Lesson
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This lesson emphasizes the connections between science and mathematics by using a performance, or authentic, assessment format. Students have the opportunity to explore applications involving their own heart. This lesson was adapted from the article, "Ideas: The Beat of Your Heart," by  Lisa M. Passarello and Francis (Skip) Fennell, which appeared in The Arithmetic Teacher Vol.39, No.6 (February, 1992) pp. 32-39.

Begin the class with a discussion of the human heart. Students should brainstorm what they already know about their own hearts. Students may discuss:

  • the location of the heart
  • the function of the heart
  • how exercise affects the hear

Distribute a copy of the How Big is Your Heart? Activity Sheet to each student.

pdficonHow Big Is Your Heart? Activity Sheet 

This activity sheet focuses on the relative size of the heart; in particular, the dimensions of the fist are related to those of the heart. Making predictions and models is an integral component of this lesson.

Read the introductory information to the students and give each student (or group of students) a ruler and a piece of string approximately 40 cm long.

Have the students measure the length and width of their fists. (Students may need to help each other measure.)

767 hand length width


Then, ask them to wrap the string around their fist, including their thumb, and measure that distance with their ruler. Some students may ask what to do, since the thumb may protrude as they make their fist. Note that students should use the same unit of measurement, centimeters or inches, throughout the entire activity. Whichever unit they choose to use will depend upon their knowledge of and experience with that unit.

Based on their fist's length, have the students estimate the length of their heart.

Next, have the students determine the distance around the fist of a teacher, an older friend, and a parent. Allow them to predict whose heart they think is biggest, given the fist measurements.

Have the students predict how long and wide their heart will be when they are sixteen years old.

Finally, have students use construction paper to make a model of their heart, using their fist as a guideline. Have the students record the length, width, and distance around their model.


Have the students estimate the weight of a human heart (less than 1 lb, or about 0.5 kg) and compare it to the weights of the following animal hearts:

  • Blue whale: 1000 lbs (450 kg)
  • Gray whale: 300 lbs (135 kg)
  • African elephant: 35 lbs (16 kg)

Learning Objectives

Students will:

  • Measure the length, width, and circumference of their fist.
  • Relate the dimensions of their fist to the size of their heart.

NCTM Standards and Expectations

  • Recognize the attributes of length, volume, weight, area, and time.
  • Understand how to measure using nonstandard and standard units.
  • Select an appropriate unit and tool for the attribute being measured.
  • Use tools to measure.
  • Develop common referents for measures to make comparisons and estimates.

Common Core State Standards – Mathematics

-Kindergarten, Measurement & Data

  • CCSS.Math.Content.K.MD.A.2
    Directly compare two objects with a measurable attribute in common, to see which object has ''more of''/''less of'' the attribute, and describe the difference. For example, directly compare the heights of two children and describe one child as taller/shorter.

Grade 1, Measurement & Data

  • CCSS.Math.Content.1.MD.C.4
    Organize, represent, and interpret data with up to three categories; ask and answer questions about the total number of data points, how many in each category, and how many more or less are in one category than in another.

Grade 2, Measurement & Data

  • CCSS.Math.Content.2.MD.A.1
    Measure the length of an object by selecting and using appropriate tools such as rulers, yardsticks, meter sticks, and measuring tapes.

Grade 2, Measurement & Data

  • CCSS.Math.Content.2.MD.D.9
    Generate measurement data by measuring lengths of several objects to the nearest whole unit, or by making repeated measurements of the same object. Show the measurements by making a line plot, where the horizontal scale is marked off in whole-number units.