Academic journal article The Science Teacher

Letter Weights

Academic journal article The Science Teacher

Letter Weights

Article excerpt

... adapted from WEIGHING #05 by TOPS Learning Systems

1. Label two envelopes like this:


2. Fill them with just enough paper to equal each weight limit. Seal them closed.


3. Given only these envelopes plus a pencil, ruler, and perhaps a pinch of clay, invent a simple method that allows you to estimate postage any time you want to mail a letter.



To devise a simple method for estimating postage rates using an equal arm lever. To develop a kinesthetic feel for one ounce.


Photocopy the lab above for each student or lab team. Black and white copies are fine.

Step 2. Roughly 3 sheets or paper plus envelope weigh 1/2 ounce; 7 sheets plus envelope weigh 1 ounce. Cut paper as needed to make precise weight standards.

Step 3. Let students grapple with this problem before helping. Hint: mention see-saw experiences.


* An ounce scale or gram balance. (In the TOPS book WEIGHING # 05, students improvise gram balances that serve well here.)

* Envelopes, legal or personal size.

* Notebook or scratch paper, and scissors. …

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