Third graders are searching for their place in the sun

Teaching Your Child

Teaching Your Child


We're studying the solar system in third grade. It is hard to imagine how vast our part of the universe truly is.

For example, Earth is about 93 million miles from the sun.

Who can picture that distance?

It helps to look at a scaled version of the universe, particularly if you've had a hand in creating that scale.

Last week during science class we were determined to do just that.

Armed with paint stirring sticks, a shovel and a measuring tape, we climbed the hill at the back of our school and planted our first stick - labeled "sun" - at the edge of the woods. Beside this stick, we placed a softball. Our sun.

Walking away from the woods along the playground, we measured 3 1/2 meters from the sun and planted our second stick, Mercury.


Actually, we measured about 3 1/2 yards because the tape measure I had was not metric. I told my students this would be an approximate scaled version of the solar system because a meter is longer than a yard.

Because the tape measure was labeled in feet and not in yards, we had to do some math as we were going along. It was fun to see them try to be the first to figure out how many feet are in 3 1/2 yards.

From Mercury, we measured about 3 yards and planted a stake for Venus.

We were supposed to tape small grains of sand to the Mercury, Pluto and Mars sticks and large grains of sand to the Venus and Earth sticks to symbolize their relative size, but we didn't because we weren't sure how to isolate a grain of sand so that we could tape it to a stake.

(Then one of my students suggested that we tape a piece of steak to the stake. We all laughed because we've been studying homonyms this year in English class. Homonyms are words that are pronounced the same but have different meanings and usually are spelled differently, too.

Well, I guess you had to be there ...)

By this time the gnats and a drizzle were putting a slight damper on our project, so we quickly moved onward to Earth, three yards farther away.

Five yards from Earth, the Mars stake was planted.

And this is when the project became a little more interesting and not so scientific. Jupiter had to be 34 meters from Mars, but my tape measure was only 25 feet. One student held one end of the tape measure. Another student walked beyond the playground along the sidelines of the soccer field. The first student stood still, handed her end of the tape measure to a third student who walked it out another 25 feet. We kept going until we had 34 yards. I again reminded the students that this was less than 34 meters, but it was close enough for our purposes. Once Jupiter was planted, we measured 41 yards to Saturn.

Then, we met our biggest challenge so far, Uranus needed to be 90 meters beyond Saturn. The students started placing each other at 25-feet increments, but they forgot one thing in their excitement of trying to see all the way back to the sun where other students were standing, waving their arms. The ones who were supposed to be standing still so other measurements could be added moved a little.

Uranus ended up in the woods on the far end of the soccer field, which is probably about where it was supposed to be.

We couldn't place Neptune or Pluto because we had run out of school property.

That was just as well because it takes Neptune 165 Earth years to orbit the sun. Nine-year-olds don't want to think about waiting that long for a birthday.

Then there's Pluto, which is no longer considered an official planet. Scientists call it a "dwarf planet," "the king of the Kuiper Belt" of comets or merely "an object." Like most people who were taught a phrase to help them remember the nine planets in order, I just can't seem to let go of "My Very Educated Mother Just Served Us Nine Pizzas." One astronomy professor suggested "My Very Educated Mother Just Served Us Nachos." Hmmm.

I will always include Pluto on a yet-to-be-planted stake, even if I can't officially call it a planet.

Lisa Tedrick Prejean writes a weekly column for The Herald-Mail's Family page. Send e-mail to her at

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