So, how do I make a circle without a compass?

[KarenB]

I am trying to make the solar system to scale to give my class (fourth grade) some perspective on the size of the planets compared to the sun. I have a chart for the diameters, but no compass. For example, the sun is 9 ft in diameter, Mars is 1/2 inch, Pluto 1/4 inch.

I suppose I could measure a string the length of the radius and simply hold it at a point, then draw a circle. The sun is the tough one since I will have to piece it together although some of the smaller ones will be difficult too. hhmmmmmm......

Thanks for suggestions or a better chart.

Karen

 

[sunkissed212]

you could find household items that are that size and then trace them. Like, a bowl, coins, lids to jars/bottles, etc...

 

[KarenB]

I am thinking that Idea might be much easier.....probably looking for the object would be the same amount of time messing with the string, etc

 

[sunkissed212]

If you have kids at home you could send them on a scavenger hunt for "round things" and then you can have lots of options to choose from to use for what you need.

 

[NotUrsula]

Tie your string AROUND your pencil for the largest one-sheet radius you need, then you can wind it a bit around the pencil shaft to shorten it to make the different-sized circles.

For that 9 ft. sun, draw it first on graph paper, then scale it out on bulletin board or freezer paper.

 

[KarenB]

NotUrsula.....I get it. See, I wish I had a bit of common sense!! Yes, just wrap the string each time instead of cutting 10 seperate pieces!!

Thanks!
Karen

 

[WebmasterAlex]

Cut a piece of cardboard to a little longer than the length of the biggest circle.

Stick a nail through it near one end and poke holes along the length of it where you need circles, way steadier than string

 

[FroggyinArk]

if you dont have cardboard handy,, try using a strip of plastic cut from a 2 liter bottle


9ft is gonna take a lot of posterboard