Purpose: Students will discover the basic concept of logarithms.
Materials: A set of scientific calculators.
Background: This lab was done in an urban seventh grade prealgebra class.


*1: When we covered this, most students could quickly see the logarithm meant the number of zeros. One student recognized that "log" meant a power of 10 and explained it to the class. Since we had not done scientific notation yet, none noticed the relationship between logarithms and scientific notation.
*2: Some students will say that log(50) does not make sense, because there is no way to multiply 10s to get 50. However, they should be able to see that: log(10) < log(50) < log(100).
Once students understand that log is the inverse of exponents [eg: 10^{3} = 1,000 <> log(1,000) = 3], have them predict values for log base 2. Use log base 10 to predict the value of the variables.


Have students compare the how logarithms represent large and small numbers to how scientific notation represents extreme numbers: what similarities and differences do they notice?
See how the Safety Index Chart connects them.







