When you wear a wool sweater, it’s hard to remember that a smelly sheep wore it first. When farmers shear sheep, or cut off all the fluffy wool, it’s washed, then spun into yarn. But how many sweaters can you get from 1 sheep? One type of sheep, the Rambouillet (RAM-boo-YAY), grows about 4-5 pounds of yarn per year, and since a sweater weighs about 1 pound, that makes about 4 or 5 sweaters. The numbers are different for other sheep — and for other animals, too. Cashmere, a really supersoft wool, actually comes from goats! It’s called cashmere because it first came from a place called Kashmir, plus “cashmere” sounds a lot fancier than “goat fur.” It takes a whole bunch of goats to make just one fancy sweater, so those sweaters cost more. Next time you wear a sweater, think about what farm animal wore it first, and just hope it took a bath first.
Wee ones: If your pet sheep gives you enough wool to knit 5 sweaters, what numbers do you say to count them?
Little kids: If you’ve knit 3 sweaters from a sheep’s wool and you then knit 3 more, how many sweaters did you make from that sheep? Bonus: 15 pounds of wool weighs only about 7 pounds after it’s washed. How many pounds of grease, dirt, grass and other junk got washed out?
Big kids: Longwool rams (the boys) can make over 20 pounds of wool a year, because they’re so shaggy. That’s just the wool alone…how does that compare to how much you weigh? Bonus: If it takes 3 goats to make 1 sweater, but 1 sheep alone can make 4 sweaters, how many more sweaters can you get from 12 sheep than from 12 goats?
Wee ones: 1, 2, 3, 4, 5.
Little kids: 6 sweaters. Bonus: 8 pounds of junk.
Big kids: Different for everyone…subtract 20 from your weight. Bonus: 44 more sweaters: 48 from the 12 sheep, but just 4 from the 12 goats (they split into 4 groups of 3).
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.