Field with corn and beans

Corn and Beans are Two of the Three Sisters


Understand a fraction 1/b as the quantity formed by 1 part when a whole is partitioned into b equal parts; understand a fraction a/b as the quantity formed by a parts of size 1/b.

Understand two fractions as equivalent (equal) if they are the same size, or the same point on a number line.


Describe the relationship between a series of historical events, scientific ideas or concepts, or steps in technical procedures in a text, using language that pertains to time, sequence, and cause/effect.

Questions this lesson plan will answer

  • Why is good dirt so important?
  • What’s crop rotation?
  • How did the Mandan, Hidatsa and Arikara keep the land healthy for centuries?
  • How are math and science used in agriculture?
  1. Play the game Fish Lake, (available to Growing Math schools, on iPad, Windows or Mac computers). If students do not have devices to access to the game, students can watch a video here.
  2. Explain that the problems of the sisters who were planting their fields with corn, squash and beans are about more than being fair, it is also good science.

Videos, PowerPoint and PDF

Videos teaching the standards are linked below. Each of these has accompanying PowerPoint and PDF links for teachers who would like to edit and expand on concepts, or print out and send home to students with limited Internet access.

What is half? This short (1:40) video explains that one-half is two equal parts, with examples of one-half as a distance between two points or as a shape divided into two parts.

Is one-half fair? Another short (1:22) video explaining that 1/2 is one of two equal parts, with examples from gardens. This concept is demonstrated by physically dragging one object over the other to see if the sizes are the exact same. Other examples include splitting a deer into two parts (weird), dividing six blankets into two equal shares and two deer each eating half of eight bushes. It is mentioned in passing that two halves make up one whole. You may want to emphasize this concept in your teaching.

Adding and comparing fractions with like (common) denominators – This two-minute animated video defines the terms ‘denominator’ and ‘numerator’. It also gives examples of comparing fractions using shapes, how much work each person has done and that stereotypical fraction example – pizza. Students are introduced to adding fractions with like denominators.


This presentation defines the words “soil” and “rotation” and gives an explanation of how crop rotation maintained healthy soil. Download it as a PDF or as a PowerPoint.

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