AACT Resources to Help You Teach Chemical Measurements

As chemistry teachers around the country are planning activities for their students, AACT will be highlighting resources from our high school resource library that can be used to reinforce topics in different units throughout the school year. We started the year with resources that could be used to support a Chemistry Basics unit. We now move on to lessons, activities, labs, projects, videos, simulations, and animations that could be used as a unit plan for chemical measurements. This plan includes the topics of scientific notation, significant figures, and unit conversion. These math based topics are very important for your students to master before they dig into other chemistry concepts. Depending on the math abilities of your students, you may want to leave some activities out.

Percent Composition:

• Before you begin the unit, take a few minutes to read Keys for Success in Teaching Chemistry: Imagination and Resourcefulness from our March 2016 issue of Chemistry Solutions. This article discusses several labs that the author uses to help teach his students to be creative and resourceful when collecting and using lab data.
• Start your year off with the Mineral Investigation Lab, which is a great introductory lab that familiarizes students with data collection and manipulation while also incorporating engineering principles and guided inquiry. In this lab, students put their problem solving skills to work as a team to determine how many specific samples of ore can be made from a lode equivalent to the size of their classroom using percent composition.
• You can then choose from one of these two labs to give your students more practice with percent composition calculations.
  • In the Percent Composition of Bubble Gum Lab, students determine the amount of sweetener in various brands of gum by determining the mass difference of the gum before and after it is chewed. By the end of this lesson, students should be able to define and calculate percent composition.
  • In the Percent Composition Lab, students calculate the percent composition of sugar in gum and the percent composition of water in popcorn kernels. By the end of this lab, students should be able to calculate the percent composition of a substance in a sample.

Metric Units:

• Introduce the metric system and units with Mysteriously Melodramatic & Maniacal Metric Measurements. In this activity, students predict the measurements of objects using metric units. They then take the actual measurements and compare them to their predictions. This activity works well as a competition, assigning points for teams based on how closely their predictions match actual measurements.

Accuracy, Precision, and Percent Error:

• Before getting into significant figures, you can introduce the concepts of accuracy, precision, and percent error with the Glassware Accuracy Lab. In this lab, students use different types of laboratory glassware to measure 50 mL of water and determine the accuracy of each piece of glassware. By the end of this lesson, students should be able to determine the accuracy of different pieces of glassware and calculate percent error.

Density:

• Use our Density Animation to introduce the concept of density and help your students visualize density on the particulate level. There are opportunities to make qualitative and quantitative comparisons between substances.
• You can then use the Density Lab to allow your students to determine the density of several liquids and solids. They then identify an unknown metal by determining its density and calculate the percent error within the class for a specific sample. By the end of this activity, students should be able to calculate the density of a liquid by measuring volume and mass, calculate the density of a solid using the displacement method for finding volume identify an unknown substance by determining its density, calculate percent error, and explain if their results are accurate or precise.
• Finish up the topic of density with the Graphing Density Lab, which requires students to collect data and use graphing to determine the density values of unknown metal samples. This activity will help your students learn to construct a line graph using Excel and analyze a linear equation to help determine density.
• If you think your students need another activity to solidify their understanding, try out our Investigating the Density of an Irregular Solid Object Lab. In this activity, students use common laboratory equipment to devise a method to measure the density of several irregular objects. They will then create a formal laboratory report using both their own data and data from the entire class. Read an article about this activity in the September 2016 issue of Chemistry Solutions.

Scientific Notation:

• Before moving on to the topic of scientific notation, read Bringing Real-Life Context to Chemical Math in the March 2016 issue of Chemistry Solutions. Then use our Scientific Notation Activity to introduce the topic to your students. In this activity, students have a button, which they move like a decimal point, to be actively involved in putting numbers into and taking numbers out of scientific notation format.
• Follow up with the Using Scientific Notation in Chemistry Lesson Plan. In this lesson, students will solve a variety of real-world problems using scientific notation. Students will listen to a convoluted radio conversation about coffee which will relate to a math-based problem that this lesson is developed around. Students will begin to recognize the benefits of using scientific notation in their calculations. This lesson includes a formative quiz, summative quiz, slides, and a radio conversation on YouTube

Significant Figures:

• Many students seem to struggle with significant figures, especially when it is taught out of context. The Significant Figures and Lab Data activity allows students to use laboratory equipment of different precision to collect data for several different metals, and then use the data to calculate the density of each. They then compare their calculated densities to accepted values and determine the combination of equipment that leads to the most accurate calculation of density.

Unit Conversion:

• Open your discussion of unit conversion with The Temperature Guys video from our Founders of Chemistry series. This video tells the story of how temperature as we currently know it evolved. The first thermometers invented in the early 1600s are very different than ones we use today!
• Follow the video with the Dimensional Analysis and Unit Conversion lesson plan to introduce the process of unit conversion. This resource includes a PowerPoint Presentation and student handout with practice problems.
• Next, use the Unit Conversion Online Tutorial Activity to have your students interact with a web-based tutorial that uses a drag and drop interface in order to learn how to convert between units of measurement using dimensional analysis. The tutorial allows students to learn at their own pace, and also provides feedback while they are solving problems. You may want to read the Chemistry Solutions March 2016 article, A Student-Centered, Web-Based Approach to Teaching Unit Conversions before using the activity.
• Get your students ready for a unit assessment with the Math and Measurement Lab. In this activity, students practice introductory math skills that will be used in chemistry all year. This includes metric conversion, significant figures, scientific notation, dimensional analysis, density, percent error, accuracy and precision, as well as using lab equipment.
• An option for an advanced culminating lab or extension for the unit could be the Nanoscale & Self-Assembly lab, which incorporates measurements, and dimensional analysis.In this activity, students determine both the diameter of one single BB and the length of an oleic acid molecule using simple measurements and volume/surface area relationships.
• If you’d like to increase your students’ scientific literacy while connecting dimensional analysis to the real world, have them read “Recycling Aluminum: A Way of Life or a Lifestyle?” from the April 2012 ChemMatters magazine or “Drivers, Start Your (Electric) Engines” from the February 2013 issue. The Teacher’s Guide for each provides a lot of conversion factors that you can use to design dimensional analysis practice problems for your students.