Ready-Set-Go STEM Activities – Mathematics My Weight on Other Planets

My Weight on Other Planets

Connection to BSA STEM Awards

This activity helps youth to complete Requirement 3, Option A, in the Cub Scout Nova Award 1-2-3 Go!

Content Notes

§  The standard approach an adult would use to find his/her weight on another planet would be to multiply his/her Earth weight by an appropriate multiplier. Very young children do not yet have the mathematical knowledge or abilities to use this approach.

§  This activity uses slide rules created for each planet to help children find their weights on other planets.

§  In all cases except Pluto, the multipliers used to create the conversion slide rules were rounded to the nearest tenth, based on figures from NASA’s Solar System Exploration website http://solarsystem.nasa.gov/planets/index.cfm. This facilitates the mathematics that children in the 1st – 5th grades are able to do on this activity, but also means that the weight conversions provide (in some cases) only crude approximations to weights on other worlds. The multipliers used are as follows: Moon = 0.2, Sun = 28.0, Mercury = 0.4, Venus = 0.9, Earth = 1.0, Mars = 0.4, Jupiter = 2.5, Saturn = 1.1, Uranus = 0.9, Neptune = 1.1, Pluto = 0.06

Get Ready

§  This activity is helped quite a lot by having an analog scale on which kids can step on and off and on which objects of different weights can be placed. A scale with numbers and tick marks between the numbers mimics the slide rules that are used in this activity.

§  Gather three objects of varying weights. (Test the lightest one on the scale first, to make sure that it is heavy enough to register.)

§  Print the slide rules on cardstock and either pre-cut them or have the kids cut them out. (If any of the kids weigh over 100 pounds or you want to have adults do the activity, then page 2 of the slide rules has add-on pieces for Earth weights between 100 and 200 pounds.)

§  Print the sliders on cardstock and pre-cut them out. Cut a transparency slide into rectangular pieces the same size as the cardstock sliders. Attach each transparent piece to a piece of cardstock with clear tape at the top and bottom. Use a ruler and a red permanent marker to draw a line down the center of the transparency.

§  Print out enough copies of the My Weight on ______ worksheets to cover your participants. Note that different worksheets work best for different grade level kids. Have pencils available.

§  Optional: make the My Weight on Other Planets poster.

§  Optional: print the planet names and pictures on cardstock, and cut into separate labels.

§  Highly recommended: work through all of the activities on all of the worksheets yourself, using the weight of a fictional kid. This will help you see the ins and outs of what each kid will have to navigate, and help you think of guiding questions to use when a kid has difficulty with a particular activity.

Get Set

§  Lay out your slide rules so that there is plenty of room for each.

§  If you have them, set up your poster near your station and post your planet labels near each slide rule.

§  Lay out the four piles of worksheets and the pencils. Clipboards or a nearby table would be helpful.

§  Set the scale and the three objects of varying weights nearby.

Go!

1.  Orient the kids to an analog scale.

a.  “Lift up each of these objects and see if you can tell which is the heaviest and which is the lightest just by sensing the weight.”

b.  “Let’s use a scale to weigh these things and see what each one weighs.” (Some discussion will have to occur about how to interpret the scale. Keep in mind that the littlest kids don’t know fractions or decimals, and will even struggle with figuring out what weight is indicated by an unlabeled tick mark. So for some of them, the best they can do is to say, “This object weighs a little more than x and a little less than y.”)

2.  Orient the kids to the slide rule’s mathematical structure – use the Moon scale for this.

a.  “Some of the marks don’t have numbers on them, just like on the scale. Can you tell what numbers belong at each mark? You don’t have to write the numbers in for each mark, but if you know how to figure each one out, that’s good enough.”

b.  “The slider is a lot like the marker line on the scale. Slide it to see how the numbers at the bottom line up with the numbers at the top.”

i.  “If you move the slider to where the number 10 is on the bottom, what is the number that matches it at the top?”

ii. “If you move the slider to where the number 8 is at the top, what is the number that matches it at the bottom?”

3.  Orient the kids to what the slide rule accomplishes (conversions of Earth weight to Moon weight).

“This slide rule is our conversion calculator. The numbers at the bottom tell us the Earth weight of objects and the matching numbers at the top tell us the Moon weight of the same objects.”

i.  “What was the Earth weight of our heavy object? Use the slider to find the Moon weight of that object.”

ii. What was the Earth weight of our medium object? Use the slider to find the Moon weight of that object.”

4.  Hand out the activity sheets and pencils.

“Now, each of you is going to find your weight on another planet and find out other fun things about weights on other planets. Each of you should take the activity page that matches your grade level.”

a.  My Weight on the Moon (for Tiger Cubs and above)

Note to leader. The slide rule for the Moon calculation has a tick mark for every whole number, although not all are labeled. It’s surprisingly difficult for kids to figure out what numbers go with the unlabeled tick marks. They will often guess randomly rather than use logic and the structure of the ruler. Try to direct them to use the information surrounding the unlabeled tick mark to figure out the number goes with it.

b.  My Weight on Mercury, Mars, & Jupiter (for Wolfs and above)

Note to leader. The slide rules for all the other worlds except the Moon have tick marks for every even number. To orient kids to these slide rules will take some extra time. Ask them to count by two’s as they point to tick marks and confirm that the verbal and written numbers match at each labeled tick mark.

c.  My Weight on Venus, Saturn, Uranus, & Neptune (for Bears and above)

Note to leader. The multipliers of 0.9 and 1.1 make it much harder for kids to think proportionally (doubling this corresponds to doubling that, halving this corresponds to halving that).

d.  My Weight on Pluto & the Sun (for Webelos and above)

Note to leader. These two worlds are at the extremes by quite a lot, and thus are much more difficult to work with. Pluto’s gravitation is so slight that it’s really necessary to use a multiplier out to the hundredths place, which makes the weights on Pluto very small. More knowledgeable kids can use fractions to indicate their weight on Pluto. Less knowledgeable kids can simply say, “I weigh a little more than/less than x pounds on Pluto. The Sun’s gravitation is so great that weights on the Sun quickly run to four digits, and many kids don’t see four-digit numbers with much regularity before 4th grade.