Educational Activity

Title: The Weight of it All

Objectives:

During this exercise, students will:

o Interpret text for facts.

o Estimate the weights of various objects.

o Critically analyze methodologies o Calculate an object's percent of total weight.

o Interpret the relative significance of various weights.

Materials needed:

* Printout of included exercise tables for each student.

* Access to the expedition website at www.soest.hawaii.edu/expeditions/mariana

Description: Before leaving port, the science party had to ensure that they had all of the right gear, including support machinery such as cranes. In order to get the right size crane, the scientist had to calculate how much strain the crane would have to handle. Although there are many factors that contribute to the strain on a crane, one of the key factors is the weight of the equipment that will the crane be lifting.

Explain to students that they will be calculating the total held by the crane as it deploys a gravity core. Ask them to brainstorm all of the equipment that would add extra weight on the crane. Students should then estimate what each piece weighs. Students can go to the daily section of our website and read the daily report on day 3, as well as the “Instruments- Sediment Corer” section in the Cruise info. Under Cruise info, students will find the actual weight of the corer. They will still have to estimate the weight of the other components such as the pinger and the core pipe.

Adaptation for older and younger grades:

Older grades may estimate what percentage they think each item will be of the total weight. Remind the students that the percentages should add up to 100.

Younger students can have a simple discussion about the various pieces of equipment in relative terms (i.e., is it comparable to the weight of a bicycle, a car, or a bus? More or less? Could a person pick it up?) Rather than using percentages, the students can discuss the topic in simpler terms such as:

a) which piece of equipment weighs the most?

b) how much heavier is one piece of equipment compared to another?

Included with this activity is an estimate sheet that students can use to record their estimations. You can download the activity sheet here.

Make copies of the sheets, and hand them out to the students. The students can fill them out individually or in partners. After the students have filled out the estimates (first table), have them compare their estimates with other classmates either in partners, groups, or as an entire class. Discuss with students the various methodologies they used for estimating. Which methodologies work best, and which are simply guesses?

Give the students the actual weights stated below, and have them write the weights in the second table. Ask the students to calculate the percentage of the total weight for each piece of equipment.

Notice that the cable, core pipe, and mud itself, are listed in pounds per unit sections. Students will first have to consider the actual length of each object, and then calculate its total weight.

The total weights are as follows:

* Note: The core that this exercise is based on (Day 3 of our trip) came back to the surface without any mud in corer. It most likely hit a rock or some other surface and could not penetrate. Nevertheless, we must calculate our weight on the assumption that the core pipe may come up completely full, and thus weigh more than it actually did.

Discussion Questions:

Here are a few questions that may be used to start a discussion.

* What are the most significant (heaviest) pieces of equipment in the gravity core setup? Did these match your estimates and expectations? What are the least significant?

* If you were to order various parts for the crane that had maximum weight limit, what limit would you buy? Are there any other factors that you should consider when maximum weight limit that a crane part can tolerate?

* When collecting cores from shallower depths (such as 2000 meters), the scientists will add extra weights (called lead pigs) to the corer. Each led pig weighs 600 lb, and up to four can be added to the corer. Why do you think these weights are necessary at shallower depths and not at deeper depths? How does the corer benefit from more weight?

Note about units: Students will encounter both metric and imperial units in this exercise. There were two main reasons for our choice of units.

a) We used the units encountered and calculated by the scientists and technicians themselves. Depths have been always been referred to on this research expedition in meters. For small lengths however, especially on equipment, lengths are referred to in feet. Likewise the specific equipments weights are recorded in pounds.

b) We also used pounds in order to help the students with their estimations by keeping the weights in a unit that is familiar to them. This allows the students to compare their estimates with objects in their day to day life.

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