Developing SEP Skills: Reaction in a Bag

The shift to 3-dimensional learning in science education not only means teachers need help and time to adjust, so do our students! How do we ready our students for this change? What’s the best way to do this? I’m not sure but I’ll tell you how I’m going to do it. Before my classes start diving into chemistry concepts I’m going to have them do an investigation in which the focus will be developing the skills necessary for using science and engineering practices (SEPs) to explain crosscutting concepts (CCCs). This way when we begin chemistry concepts we have a reference point. The disciplinary core ideas in this investigation are (hopefully) review for my students (matter is made of particles and energy flows). To do this, I’m going to take an old lab (Reaction in a Bag) and refine it to fit my needs. You’ll find everything below!

Title: Reaction in a Bag; Topic: Developing SEP Skills

Focus (Goals): Students will begin developing skills focused on collaborating, analyzing data, constructing explanations based on evidence, and communicating information.

Student Science Performance

Engaging Learners


Carrying Out an Investigation: In pairs, students perform “Reaction in a Bag” investigation to collect observations.

(Teacher Hint: Teachers give students the “Reaction in a Bag” procedures. Students should place 1 scoop of baking soda and 2 scoops of calcium chloride in opposite corners of a ziplock baggie. In a small beaker, students mix 10 mL of deionized water with 5 drops of an acid/base indicator, such as phenol red. Pour this mixture into the ziplock bag and quickly seal bag, squeezing out as much air as possible. Ensure all chemicals mix together and record observations).


Communicating & Asking Questions: Students engage in a classroom discussion about their observations made during the investigation. Students begin asking questions about the causes for their observations.



Planning and Carrying Out an Investigation: In pairs, students develop investigations to address 1-2 of their questions. Students carry out their investigation(s) and record observations.

(Teacher Hint: Students should “drop” 1-2 chemicals for each investigation. Allow student pairs to determine which chemical(s) they want to drop. )


Analyzing and Interpreting Data: Students begin constructing preliminary explanations for the role of the components in their system. Students should analyze and evaluate the data to determine the best evidence that will support their explanations.

Communicating: Whole class develops data tables to reflect observations made of each system by each group. Students can analyze the interactions within each of these smaller systems and begin connecting this evidence to the observation made of the larger system.



Analyzing and Interpreting Data: Based on whole class data tables, student groups revise and/or elaborate on their explanations for the causes of their observations for the larger system.

Developing and Using Models: Student pairs should develop models that illustrate interactions between chosen chemicals and the resulting observations (cause and effect).


Engaging in Arguments from Evidence: Student pairs argue for why the evidence they have gathered supports the explanations for their observations. Students utilize their models to communicate their explanations and arguments.

Assessment of Student Learning

  • Students will be able to identify causes and effects for observations made during an investigation.
  • Students will be able to construct explanations based on evidence for the causes of their observations.
  • Students will be able to analyze interactions within a system.
  • Students will be able to develop explanations for the role of various components of a system.
  • Students will be able to revise explanations based on new evidence.
  • Students will be able to argue for why the evidence they have gathered supports their explanations.

Remember it is not necessary to understand the precise chemical events that take place during this investigation. This activity provides an introduction to developing SEP skills that’ll explain CCCs. I will not allow students to hide behind science terms; I want to make sure students practice constructing explanations that are tied to observations, not can they use the terms “endothermic” or “exothermic”, etc. While I certainly hope they remember some of these simpler DCIs (they are 9th/10th graders after all) I will not be evaluating them on it for this particular activity. Below you’ll find an easier to read table that highlights the DCIs, SEPs, and CCCs used in this investigation.

Screen Shot 2016-08-28 at 9.05.32 PM

My Chemistry 1 classes will be doing this investigation this week. Next weekend I’ll update this post with pro’s, con’s, and pictures from my classes! (You can find that blog post here.)

Download the 3D lesson plan by clicking on the link below! It’s a Word doc so it may/may not immediately open when you click on it; depends on your computer set up.

3D Lesson Plan: Reaction in a Bag

What ideas do you have for how you’ll teach the skills necessary for science and engineering practices?

4 thoughts on “Developing SEP Skills: Reaction in a Bag

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