Teaching the metric system is one of the first topics we cover in my biology class every year. I teach it as part of our Introduction To Biology unit, but you may find it works better to teach it as a stand-alone mini unit. Either way, your students’ ability to both understand and apply the metric system is critical to their success in your biology class.

**Introduce to the metric system**

While it is likely that your students have been taught the metric system in prior classes, the amount of information they remember will vary greatly from student to student. When introducing the metric system to my students I often will start with a bellringer activity that helps me get a snapshot of what they remember.

Once I have a good idea of the level of understanding my students, I bridge into my metric system powerpoint notes. As I have mentioned in another post, I prefer the cloze or “fill-in-the-blank” system of note taking in my science classes. As someone who grew up struggling to keep up with taking notes that I didn’t get a chance to comprehend much of the information during lectures, I try to minimize the amount students have to write to a minimum while still keeping them engaged in the lecture,

**Include a metric system prefix table**

To help my students remember the metric system prefix name, I use the phrase “King Henry Died Monday Drinking Chocolate Milk” as a mnemonic device. It’s a sentence every student can remember and I go so far as to have them write out the first letter of each word on their quizzes if they get stuck so they can remember the order of the metric prefixes. I also like to use a table as a visual to help my students understand the prefix sequence. The picture below is from my introduction to biology lecture notes (I chuck the metric system with both teaching the scientific method and a review of graphing) for the first unit we cover in my class. We also build on words they are familiar with already such as a kilometer or a milliliter.

**Teach How To Convert Within The Metric System**

Once my students have a grasp of the metric prefixes, we begin learning how to convert between the decimal system of measurement. I remind them that the process is the same regardless if they are measuring in meters, liters, or grams. I have found my students are the most successful when they create a number line that is horizontal versus writing the metric system prefixes in a vertical formation.

I keep a metric system conversion chart visible while I have students get into small groups and complete a few practice problems. This gives me time to walk to the room and help out students who are not picking up the lesson as quickly. This also allows my students a chance to help each other out if they are understanding the metric system conversions. At this point you could either give a metric system worksheet as a homework assignment or include it in an interactive notebook.

**Teach How to Calculate Metric Conversions**

Once my students are comfortable converting between metric system prefixes, we introduce how to convert back and forth between our United States system of measurement. I give my students the conversion figures with the goal that they can calculate the correct answers on a quiz, lab, or test. Chances are your students will not know that there are 2.2 pounds per kilogram or that 1 inch is equal to 2.54cm. This lesson also gives students an opportunity to build confidence in the arithmetic skills, something that most students could use extra practice with.

**Check For Understanding With A Metric System Lab**

As one of our early labs of the school year, our metric system lab helps students improve both their ability to weigh and measure objects as well as calculate and convert metric units. Depending on the supplies you have available, you can customize a lab activity that works for your classroom. At each lab table I give my students different measuring devices: metric ruler, graduated cylinders, and a triple beam balance (even if we will use a digital scale for most labs later in the year). I then have my students weigh and measure various items. If this is your first lab of the year, you could add in your safety contract and teach your lab safety procedure as well.

**Metric System Review**

The class before we take a unit test I like to use a review game to give my students a chance to determine how much of the content they know (and how much they still need to study). Task cards are a great review activity that can be used in your class. For some units I will have students walk the room and answer the questions I have set out on the lab tables. And other times I will play a “family feud” style game where a kid from each team will have to come up to the front of the room and answer the question for their team.

**Finish Your Metric System Unit With An Assessment**

The final step in teaching the metric system is to have some type of summative assessment. As I mentioned earlier, I include teaching the metric system into a larger unit that usually takes 2 or 3 weeks to cover. If you are teaching the metric system as a stand alone topic, you may be able to cover it in 3 or 4 days. Your assessment can be a combination of vocabulary words, metric system prefix matching with the numerical meanings, and conversion problems.

**Final Thoughts**

I always remind students that the metric system will be used throughout the school year. It’s not going anywhere. You may find it is a topic you want to review periodically before labs as a refresher. But once your students have mastered this topic, the rest of the school year will be much easier for them in your science class.