The purpose of this lesson is to continue building students’ facility in working with logarithmic expressions and equations. Students practice interpreting logarithmic expressions and evaluating them mentally by playing a game of “war.” They also begin to use a calculator to evaluate logarithms. They notice that most values produced by a calculator are also approximations rather than exact values.
In playing the game and evaluating log expressions repeatedly, students look for regularity in how log values could be compared (MP8). They may notice how the size of the parameters in a log expression relates to its value and use their observations (for example, that certain numbers produce positive or negative log values) to make comparisons more efficiently and accurately (MP7).
- Calculate the value of a logarithmic expression using estimation or technology.
- Justify (orally) why one logarithmic expression is greater than another.
- Let’s find some logs!
When printing and cutting up cards from the blackline master, decide whether to use only the first 20 cards, which contain only logarithms with integer values, or to also include the last 10 cards marked “challenge,” which contain logarithms with non-integer values.
Provide students with access to scientific calculators during the last activity and the cool-down.
- I can use known values of logarithms to estimate the value of other logarithms.
- I can use technology to determine the value of a logarithm.
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