Classroom Menagerie of Mathematical Knots

Description

By making a variety of knots students will: At the end of the activity, each student or small group of students will have many knots to examine and work with. They can use these knots in other activities.

Materials

Instructions

Ideas for discussion

Materials

Instructions

  1. If this is the students' first experience with knots, give them some background about the mathematical study of knots. Show how mathematical knots are closed loops with the ends tied together.
  2. Explain that each student or group will be making several knots. By making knots yourself, you will be able to understand a lot of things about the structure of knots. Then we will all have quite a few knots to study and experiment with.
  3. Have the students look at the knot in the upper left hand corner of the collection of knot diagrams it is a trefoil knot . Draw this knot on the board and show students how the broken line in the diagram means that the strand of rope goes under the other strand when the two cross.
  4. Using a large strand of rope, demonstrate to the students how to form a trefoil knot according to the diagram. It is easiest to make knots from diagrams on a flat surface, rather than holding them in your hand where they can flop around. Use a slanted board to demonstrate to the whole class, or form the knots on the table, the floor, or other flat surface and have the students gather round and watch. Show how you fasten the ends of the knot together with tape so that the closure is secure and smooth.
  5. Have the students make the trefoil knot . Help them verify that the knots have been made correctly. Be especially careful that the students have not made the other trefoil knot --the one to the right of it in the collection of knot diagrams--by mistake. Encourage students to help one another, to explain the method or techniques that they used to make the knot and to check that it was correct.
  6. When students understand how to make knots from the diagrams, tell them which other knots they should make. Choose four or five knots that everyone will make. Then allow students make two or three other knots of their own choosing from the collection of knot diagrams.
  7. It is very important that the knots be produced exactly as they are in the diagrams. (If the knots aren't exactly right now, this will pose a problem later if the students do the activity Are they the Same or Knot . In that activity, students combine their knot collections and examine knots which are identical.) As the number of crossings increases, it is easy to make mistakes. Have students pair up and compare the knots that they have made to be sure they are indeed identical. If the knots appear different, have them study the knots and the diagram carefully to determine what the problem is. When one group has completed a set of knots, they should ask members of another group to verify that they have made the knots exactly as they are in the diagrams.
  8. When the knots are finished and verified for accuracy, have students label them with their names. Also, be sure the knots are strong, and not likely to pull apart, because they will receive a lot of use in further activities.

Ideas for Discussion

  1. Debrief the activity with questions similar to the following:
  2. Some of the knots, such as the trefoil and the figure-eight knots have names. Students may want to name their other knots.