Sneaking Math Into The Garden
Pumpkin growth rates
Pumpkins can be measured through the growing season. When the plants begin to bloom, watch for small pumpkins that have been pollinated. The blossom will fall off and the tiny pumpkin will begin to swell. Choose several pumpkins to measure. Mark them with numbers attached with very loose ties to the stem. If necessary, change the ties for larger ones as the pumpkins grow. A tight string will prevent the pumpkin from growing properly.
Every week measure the circumference of the pumpkin using a flexible tape measure (one used for sewing works best). Measure around the widest part of the pumpkin and be sure to measure the same place each week. Convert any fractions into decimals for recording.
Area to measure
Record the measurements on a chart (see example) each week. Convert the circumference measurement to a diameter measurement. Then convert the inch measurement to centimeters. Chart all the measurements on a graph (see example). Compute the average weekly growth (see example).
If you are growing a small to medium size pumpkin a weekly weighing can be included. Use a flat top scale or balance and gently set the pumpkin on the balance. Remind the students that this is only an estimate. The weight will be a little off because of the vines attached to the plant. Again chart and graph the weight changes and average the weight gain and covert weight from pounds to kilograms.
Example of measurement and weight recording
Date / Circumference / Diameter / WeightInches / Cm / Inches / Cm / Pounds / Kg
7/7 / 1.5 / 3.8 / .47 / 1.2 / .25 / .11
7/14 / 6 / 15.2 / 1.9 / 4.8 / 1.8 / .82
7/21 / 12.75 / 32.4 / 4.05 / 10.3 / 2.5 / 1.14
7/28 / 16 / 40.6 / 5.09 / 12.9 / 3.6 / 1.64
Total growth / 14.5 / 36.8 / 4.62 / 11.7 / 3.35 / 1.53
Average/week / 3.6 / 9.2 / 1.15 / 2.9 / .84 / .38
Example of charting circumference: Note this was done in Excel for ease of placement in this document. Students should do actual graphing by hand on graph paper to reinforce skills.
Green beans
Green beans can be counted, measured and weighed to learn how many beans the plants will produce by number and weight over the entire growing season.
Plant one or more rows of bush green bean seeds following package directions. Thin plants by choosing the best ones, and leave room between individual plants so branches are not mixed up when the beans are picked. When the beans are mature choose 5 or 10 plants to monitor. Put a numbered stake or marker on a string around the base of the plant.
Pick beans twice a week. Beans become overripe very quickly and you are looking to pick beans that are ready to eat. Record the following information each time:
1.the number of beans from each plant
2.the length of each bean
3.cut each bean in half and measure the diameter (with small beans it is easier to use a mm ruler and then convert into inches)
4.the weight of all beans from the plant and then calculate the average
Convert all inch measurements from fractions to decimals for recording and then into cm and ounce measurements into grams or kgs. Total the number of beans from each plant and calculate the average number of beans per plant.
Example of bean data
Plant #1 June 25
Bean # / Length / Diameter / Total WeightInches / Cm / Inches / Cm / Ounces / grams
1 / 3.8 / 9.7 / .33 / .8 / 3.1 / 87.9
2 / 3.5 / 8.9 / .4 / 1 / Average weight per bean - .62 oz or
17.6 grams
3 / 3.6 / 9.1 / .33 / .8
4 / 3.75 / 9.5 / .4 / 1
5 / 3.8 / 9.7 / .4 / 1
Average / 3.69 / 9.38 / .37 / .9
Add weight and number of beans from all plants and compute the average weight and number of beans per plant. Graph this information.
What did it cost?
Students can learn to compare the price they would pay for vegetables in the grocery store to an estimated cost for growing their own. Explain that not all costs to grow their vegetables can be included because water is included in the schools water bill and hard to figure and they don’t have to pay full price for tilling the ground or fertilizer. Older students could try to figure these things out. Younger students can use the easily available costs.
Choose several vegetables to include like lettuce, broccoli, tomatoes or sweet potatoes. Record the cost of seeds or plants.
Students can use weekly grocery ads or trips to the grocery store to find the current price for their vegetables.
When the vegetables are ripe, harvest like you normally would. Before preparing the vegetables to eat or giving them away, weigh them and record the weight. Do this for the entire harvest season.
An example of figuring the cost:
$.75 for 6 broccoli plants from KCCG
$10 for labor (help students figure what they think is a fair labor cost, this is only
an example)
$2.29 per pound for broccoli from the store
When the harvest is done, add up the weight of each type of vegetable. Multiply the total weight by the cost from the store for the same vegetable.
Harvest from 6 broccoli plants: 17 pounds
Cost of 17 pounds of broccoli from the store: $38.93
Cost to grow your broccoli: $ .75 for plants
$10.00 for labor
$10.75 costs
Cost of broccoli from store $38.93
Cost to grow own broccoli $10.75
$28.18 amount broccoli from the store costs over
homegrown broccoli
Questions to answer
1.What would happen if you measured the pumpkins in a different place every time?
2.Go to this web site and look at the pictures of pumpkin flowers.
Look at the 2 types of flowers, read the article and answer these questions.
a.What does the male flower produce?
b.What is the knobby thing under the female flower?
c.Which flowers do you see first? Male or female?
3.Go to this website to find the world record pumpkin.
Subtract the weight of your largest pumpkin from the weight of the world record pumpkin. What is the difference in size? ______Now for fun, read about giant pumpkins and how they are grown.
4.How would having your bean plants too close together cause problems with picking and counting the beans?
5.What is the formula for:
a.Changing inches to centimeters? ______
b.Circumference to diameter?______
c.Pounds to kilograms? ______
6.Maybe the cost to grow one of your vegetables is higher than you would pay in the grocery store. Why would people prefer to grow their own, rather than doing the easy thing by picking it up in the produce section?