Half of a Half of My Garden Plot
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Half of a Half of My Garden Plot
Grade Level 3rd
Subject Area: Math
Core Curriculum NF1: Standards Met: Introducing fractions
30 minutes to set up demonstration plot
45-60 minutes on first day, and 10 minutes to check back each week.
- Unplanted garden plot, 4’x8’
- Ball of string
- 24-foor string tied in a loop
- Craft sticks
- Bright crayons
- Garden journal
- Seedlings to transplant/seeds
Students will demonstrate fractional parts of a whole by consecutively dividing an area by increments of one-half. After the divisions are made, the whole can be seen as the sum of its parts.
- Cut a 24-foot length of string for each group and tie the ends to form a loop. These will be used to outline practice plots and your garden plot.
- On a lawn near your garden, stack out a 4’x8’ plot for your demonstration using craft sticks. If you have time constraints, stake out a plot for each group of students as well.
- Gather students around the demonstration plot
- Inform them that when growing plants it is important to know the amount of space each plant needs as a mature plant.
- Hold up a plant, such as a cabbage, and tell them that the area needed for a full-grown plant is 1 square foot. Today we are going to learn a method to divide garden beds so our plants will have enough room.
- Tell students that you are going to divide this plot into two equal halves. You then will divide one of the halves in half again. You will do this until you have a plot that is just big enough to grow one plant
- Have volunteers help you section off the demo plot. Have one person tie the end of the string to a craft stick and stick it in the ground in one corner of the plot. Ask another student to unwind the string along the length of the plot to the opposite end.
- Cut the string so it measures the length of the plot with a little extra to spare. Let the youth remain there, holding the point on the string that reached the end of the plot.
Finding the Midpoint
- Ask the group to determine the point on the string that is half the distance from one end of the plant to the other. Let them estimate the location of the midpoint. Have a student volunteer pinch the spot on the string they think is the midpoint.
- Show how to “fold” the string into two equal lengths by having the individual with the loose end of the string (untied end) walk back to the end that is tied to the craft stick.
- Look at the point where the volunteer is pinching the string and the two lengths of strings that are created by the fold. Does the folded string match up so that each of the two new lengths are equal? If not, adjust the lengths of string so they are equal and have the volunteer pinching the string move to the midpoint. Once the midpoint is established, ask the volunteer to put a craft stick in the ground to mark the point.
- Have the student with the untied end of the string walk back along the side of the plot, tie the string to a craft stick, and put the stick in the ground.
- Cut another piece of string that can span the width of the plot with a little extra to spare. Tie one end of the string to the craft stick marking the midpoint, and let someone take the other end to the opposite side of the plot. Ask for ideas of how to make 90-degree angles at the division.
Half of a Half of a Half of a…
- Have the group look at the plot now divided into two equal areas. Tell them you want to divide one of the halves in half. Ask for ideas of how to proceed.
- Guide the group in finding the midpoint along the string that was just laid. Use a piece of string to divide the half into two equal areas as you did above. Point out that these two new “halves” together are equal to the first half. They are “half” of the original half. Each is one-fourth of the whole plot. Look at the three areas you have created and name the fractional parts of the plot. (one-half, one-fourth, and one-fourth).
- Choose one of the one-fourth areas to divide again. Divide this piece into two halves. Point out that each of these “halves” is one-eighth of the whole plot, and that as more halves are made, parts are quickly getting smaller in area.
- Continue taking halves until you have a 1-foot-square plot. Tell them that this is the space needed for one full-grown plant and so you will stop dividing at this point.
- Have the students tell you how the plot was subdivided into parts by successively taking “half of a half.” Check that they know why you stopped where you did. The plant needs a 1-foot-square plot.
Dividing the Plots
- Once everyone grasps how to divide a garden plot, assign each team to their own 4’x8’ plot on the lawn and instruct them to stake out a plot with the string loop and craft sticks. When all teams have finished, have the group look at one of the team plots. Ask questions like “does it look like the demonstration plot? How does it differ?” and “How many times did you divide your plot in half?”
Planting in the Garden
- Gather your group around the planting bed in the garden. Together divide the plot using the same halving technique until you produce 1-square foot plots.
- Show the class the seedlings you brought to plant. Inform them of the size of the area needed by each when it is a mature plant. Have them look at the seedlings and decide where each plant should go. They may need to divide some of the areas into smaller plots.
- Have the students label craft sticks with the names of their plants. Place the appropriate label next to the seedlings and water.
Ask students to recall how many times they had to divide the garden plot in half to make individual square feet. Ask them how many square feet a 4’x8’ plot produces? What is another way to find out the how many square feet (or the area) are inside a rectangle? Multiply length by width.
Credit for Adaption
Lesson taken from “Half of a Half of My Garden Plot” in Math in the Garden, National Gardening Association, 2006, pgs. 39-42. Adapted by FoodCorps