Here is the third lesson in using benchmark percents. This lesson begins with quiet reflection by the students. I want students to explain how to use the benchmark and to provide an example (MP3). I used to teach the 1% and 10% benchmarks and their offshoots in one day. I found that this caused confusion for too many of my students. This third day allows students a chance to put together what they have learned so far.
Students might need an example for how to answer #4.
Example: to find 16% percent of a number you might use 10% + 5% + 1%.
I hope for 99% students realize they can use 100% - 1%. If not, I'll ask if it is possible.
After about 5 minutes of quiet reflection, I'll call on volunteers to share their responses. The students will then critique the explanation presented by their peers. Students will be asked to consider whether each explanation is written clearly enough; does it clearly explain how to find 10%, 5%, or 1% of any number?
Some students may already be familiar with other ways to find percents - divide a value by 2 for 50% or divide by 4 for 25%. These are worth discussing if they come up. I would ask why can we divide by 2 for 50%? 4 for 25%?
This next section will be done on whiteboards. Before we begin, I'll remind students to use the whiteboards for the current math problem only (no notes to friends, drawings, etc). Also, do not erase the board until I ask.
The top of the resource provides an example of how I would like to see students lay out their work. It does not have to be identical to this, but I would like to see each benchmark percent and the corresponding value.
The exit ticket has 5 questions. By now students should be able to answer the first 4 with relative ease. The fifth question asks for 0.5% of a value. I am assessing whether students understand that 0.5% is half of 1%. Any valid explanation would be fine: will someone say divide the 5% value by 10?