Jazz Up your Sig Dig Lesson!

Written by: chemteacher • Edited by: Benjamin Sell
Updated Jun 30, 2009

Help the topic of Sig Digs come to life with an easy, stimulating activity. Get students out of their seats and let them put the concepts you just taught into action. This 2-part series not only provides the lesson, but an explanation on how to teach it as well!

Just how thick is aluminum foil?

This activity is a perfect way to get students to practice using significant digits in the laboratory. The idea is that each lab group will be given a small rectangular piece of aluminum foil, a centimeter ruler, and access to a balance. That's all the set-up required! A science teacher's dream!

Explain to the class that they will be measuring the thickness of a piece of aluminum foil, but that it cannot be done with a traditional ruler because the foil is just too thin.

How to find the answer

Have students brainstorm possible methods for solving this problem.

Tell the class that one possible way to solve the problem is use the denisty of aluminum, which is 2.70 g/ml. If you know this, as well as the mass of the aluminum piece and the formula for density (D= mass/volume), you can solve the formula for the volume of the piece of aluminum foil.

Once you have calculated the volume of the foil you may then use the formula for the volume of a box, which is V = length x width x height. It is easy to measure the length and width of the foil using the centimeter ruler. Substitute the values into the volume formula and solve for the height. This represents the thickness of the aluminum foil.

Incorporating Sig Digs

In addition to practicing density calculations and measuring techniques, this activity provides a great opportunity for significant digits practice.

First, it is necessary to help students understand how to read their centimeter rulers. (In other words, what decimal place can the rulers read to?) Secondly, direct students to count the number of signifcant digits in their measurements. Third, remind them that they need to round their multiplication and division calculations to match the number of significant digits in their original measurements.

The next article in this series, titled "How Thick Is Aluminum Foil: Student Version," contains a handout that you can cut and paste into a word-processing progam and use with your students. Feel free to adapt it to the level of your students. Steps may be added or omitted to make the process more inquiry-based, as well.