Hanging By a Hair

standards: 5.NBT.7,   5.OA.3,    5.MD.1

Act 1

Watch the video

  1. How many pieces of hair would you need to support your body weight?
  2. Write down your estimate
  3. Write down an estimate you know if too high? Too low?

Act 2A

What information would you like to know?

How strong is a single strand of hair?  Since we need to determine the tinsel strength of your hair, how many pennies would a single strand of your hair support until it breaks?

  1. Write down your estimate
  2. Write down an estimate you know if too high? Too low?

admin-ajaxThe test: Take a single strand of hair and securely tape one end to a pencil.  Wedge the pencil into the stack of books so that the pencil is sticking out and the hair is hanging down. Securely tape one penny onto the strand of hair and see if the hair can hold it. Keep taping pennies to the strand of hair until it breaks.

Act 2B

Now that you know how many pennies your hair will support what do you need to know to find out how many pieces of hair you need to support your body weight.

a penny weighs 2.5 grams OR 0.08 ounces

in case you forgot…16 ounces in a pound AND approximately 456 grams in a pound


Act 3

Compare and share solution strategies.  How appropriate was your estimate?

Act 4 (The Sequel)

  1. Can you find the rule that would determine how many hairs would be needed for a person of any weight?
  2. Can you write it as an expression?

Click the link here to find more of My 3-Act Lessons