Category: ExploreFlipApply

Playing with Chemicals

photo (1)

Data requirements for lab.

This week, I had the AP students do some very simple labs focused upon law of conservation of mass, but connecting it to stoichiometry. Students mixed a white powder with a liquid to produce a gaseous product (massing beakers initially, with and after, see image at right), share their data on the board, then graph the class data on a TI calculator (see image below).

photo (2)There were a couple of points to this. First, the initial share was with total mass before and after and the students see they don’t match — the gas was lost. This means different data is needed, but it still has to come from what they collected. Why not compare the mass of the gas (that lost mass) and the mass of the solid? When this is graphed (solid mass on the x-axis, gas on the y), a linear relationship is evident; further supported by the linear regression done. [I’m reading my notes from this summer, one-finger-typing my lists and such and my students were waiting on me; even made a point of telling me to just ask them what to do next time as they do this all the time in math. They enjoyed that way more than they should have.] We do discuss just what the linear equation means (y=mx+b). In this case, y = 0.502x +.055, the slope tells them that 0.502g of gas is produced for every 1g of solid used and that there’s error because ‘b’ has a value other than zero (the error in the class data).

Then, the second point of the discussion — the part I did not carry off as well as I wanted — determining the ‘ideal’ relationship for this solid and this gas. Enter the chemical reaction (just in case they had not determined it was baking soda and vinegar) and I place the molar masses of each substance underneath, totaling the masses of reactants and products to show the masses are equal, show conservation of mass. This wasn’t exactly a revelation to this group, but I didn’t let them tell me what the ideal equation for the line should be: the total mass of the gas divided by the total mass of the solid. This is the point that gets us to stoichiometry. As soon as you start comparing the masses, ideally seeing that molar ratio behind the mass comparison because molar masses were multiplied by coefficients, you are performing the basics of stoichiometry calculations.

They answer four questions

  • How good is your point? Explain. [Their point on their graph has a smiley face above it.]
  • How many grams of gas should you lose? Explain how you know.
  • ? g of gas if 5g solid used? Show 2 ways.
  • ? g of solid if 5g gas produced? Show 2 ways.

All of these are answered by evaluating the graph and their point on the graph

  • it’s good because it’s close to the ideal line
  • more or less gas should have been lost — based on whether it’s above or below the line (getting to another rabbit trail in the discussion about the source of error: below the line, not enough gas produced; above the line too much; and what could have caused this)
  • the first way, find it on the graph; second way, calculate by multiplying masses (factor label)
  • the first way, find it on the graph; second way, calculate by multiplying the masses, but inversely as the gas needs ‘canceled’

The goal with this set of labs is to have the students (1) want this ‘proved’ again to see this truth with a different reaction; (2) lead to other questions like what the graph would look like if the amount of solid is varied with the same amount of liquid or vice versa, keep the solid constant and vary the liquid; i.e., predicting limiting reagents. Again, the whole point is to get them to take the data, see the linear relationship, but ask why and want to see more data to prove it — not exactly carried off in this way. Instead, I had them do the lab several times, plug in our data, examine the graphs produced, and see that, “yup, it’s linear, again.”
My problem here was my approach. This would work well for chemistry if I fix the conservation of mass introduction & link to the results — what does conservation of mass mean? reactants should equal products, so we balance the equation, but is there another way?…work to masses of reactants and products and what this means for the lab, compare the line produced to the ideal one they find…ask if this is the case all the time? is it predictable? Push for the questions because it’s new. AP, on the other hand, should be about predicting the results, predicting the graph, predicting the ideal line. This information is not new it’s review, so, I needed to take it to that point instead of getting caught in no-man’s-land between new & review where I lost some of the effectiveness of the enterprise.

[Thanks to Jim Cortez for sharing this during our summer APSI.]

Exploring Chemistry

I’m liking the challenge and the potential impact of ‘exploring’ each concept before students actively study as I attempt to implement explore-flip-apply. My twist, though this is blatantly stolen, is to have the students reflect on &/or explain the exploration in a blog post.

My post is coming up prior to any data to support an assertion of actual improved outcomes and increased learning. However, the questions asked, exposing the interconnections between concepts, was absolutely amazing today.

WaterElectrolysisThe activity, using a 9-volt battery to eletrolyze water, is part of my first unit and I wanted it to both review and set the stage for stoichiometry. There were four questions I wanted them to answer:

  • What is the balanced chemical equation?
  • Is there qualitative evidence to support the balanced chemical reaction?
  • Could you collect quantitative data to ‘prove’ the balanced reaction? How?
  • Can you draw a particle diagram(s) that models what’s going on in this reaction?

I had the equipment out — battery, sample cups with tacks, small plastic test tubes, and two different salt solutions — and we got started. One of the first questions asked was how to capture the gas in the test tubes. This is not a question to be taken lightly, since the point was to have the captured gas push water out of the test tubes to visually see the difference in the amounts. Rather than let the students struggle, I made a mistake I think, I showed them what to do — fill the test tubes with the salt solution, invert, and quickly fill the sample container with more solution. The whole apparatus is now placed upon the battery. Immediately, bubbles begin forming, an unmistakable difference in rate apparent. The students get theirs going.

I wanted them to work alone to answer each question first, thinking about them while they watched the reaction, then using their ideas during discussion. Again, I think I jumped the gun a bit — struggling is not something they enjoyed — and I cut this time too short.

We jumped into the group discussion with the first question and a uniform response was provided, a balanced equation for decomposition of water. I jumped to the last question here, I’m leaning toward making it the second question next time, and, again, a confident reply of ‘sure’ from the group. The second question was the first divergence from my script: how can you know that the gases are actually hydrogen and oxygen? The observations also helped to push this question forward from left-field. After a bit, all the test tubes lost the apparent doubling of gas in one test tube versus the other; there was still more in one, but it didn’t look like twice as much. To try to show this, I introduced some UI to the solution and filled the tubes and sample cup again. One complication, the salt solution used sodium bicarbonate.

Shifting our focus again, during this time of waiting and watching, we jumped to the third question; surprisingly tougher than I thought. They were still focused upon how to measure the products, how to verify they were oxygen and hydrogen….I just wanted them to think how a balanced equation had to be based on an equal mass before and after. So, I kept trying to push them back to the law of conservation of mass, the law behind a ‘balanced chemical’ reaction. Again, I gave in, and just told them this.

Concluding the UI variation….

Gases are now being produced in a blue solution, but bless it, one of them begins to lighten (I won’t go so far as to say it turned yellow, but it did become less blue). This lead to what exactly this change in color meant. We take a turn into pH, the equilibrium of water ionization and baby steps to electrochemistry. Using the equilibrium equation as a new starting point, I try to encourage them to work out what’s ‘left’ when each gas is formed, pushing them to visually separate the equation in their mind and the bell rings.

I try to frantically throw information at them as they ready for the next class and assure them we’ll do a quick finish-up tomorrow, in class, and their blog post will be due tomorrow now, too.

[Follow-up: so quickly refocused upon goals from yesterday, added some explanation about self-ionization of water, rewriting the equilibrium equation twice. Without going into detail on redox, so just in terms of particles, if hydrogen is removed (or oxygen), seeing what is left behind helps to explain why the indicator changed color, why the pH is different. I’m really hoping this turns into a seed to reap from in future concepts.]

Anatomy Re-do: Muscle Breakdown

My goals in Anatomy need modified. I need to streamline my standards and tweak my learning objectives for this course. The existing objectives I operate under were slightly modified from the local community college when work was done on an articulation agreement (i.e., students that earned an A or B would also receive credit from the community college upon enrollment).

To that end, I’m going to attempt to organize the presentation of material and practice activities, attempting to link these to the purpose/goals/objectives of each system. This is a process I’m going to go through for each system.

The Muscular System is first for one reason: the amount of anatomy and physiology content. This is the first system where the depth of physiology becomes an issue: everything from the details of the action potential by way of the electrochemical gradient to the chemical cascade leading to contraction to the metabolic pathways responsible for energy production allowing contraction, not to mention the Cori cycle and Oxygen debt. Basic anatomy includes micro- and gross anatomy (as seen in the skeletal system) including knowing certain muscles, i.e., memorizing their names, and the method of nomenclature, but is complicated by the three tissue types, by the impact of the microscopic arrangement upon the actions of the organ (banding, sarcomeres, SR and T-tubules, endo- to epimysium, fascicle arrangement) and the conformational changes associated with contraction, not to mention the difference in isotonic vs. isometric contraction, and linking it to origin/insertion and action. There’s a lot of information and a fair amount I’ve left off this list.

Below, I’m listing the current objective & items/activities I use. Below that will be the potential change or questions I have about the changes and I would greatly appreciate suggestions and critiques.

System Introduction

  • Body Atlas Video segment “Muscle and Bone” — bridge from skeletal system to muscular system (25 min)
    • backchannel during video for comments and questions

1. Describe the properties and function of muscle tissue

  • Flipped 6.1 — gross anatomy notes: intro to muscle function, quick review of different muscle types (both tissue and functional skeletal), nomenclature, origin/insertion, lever action, movements, muscle names/locations (14.52 min)
    • Quick listing of the functions of the muscular system
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion

2. Identify the principal axial and appendicular muscles of the body; including identifying origin, insertion, and action of ten muscles

  • Blank Anterior & Posterior Muscle Man — fill in blank chart
    • Identifies key muscles of the body
    • Done individually, in class
  • Anatomy ColorPlates Packet — copies of relevant pages in the Anatomy coloring book of major axial and appendicular muscles
    • Anatomy is visual; this provides reinforcement of knowledge
    • Done individually as homework
  • Flipped notes 6.1 — gross anatomy notes: intro to muscle function, quick review of different muscle types (both tissue and functional skeletal), nomenclature, origin/insertion, lever action, movements, muscle names/locations (14.52 min)
    • Does provide different images for principal muscles of the body
    • Understanding nomenclature reinforces anatomical awareness and provides leeway in remembering different names
      • Ex. Rectus Femoris vs. Rectus abdominus — found in the thigh or abdominal region; remembering the ‘rectus’ means straight bonus information
    • Quick review of the requirements of origin or insertion, linked to basic body movements (setting stage for function of muscles)
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Skeleton Diagram Insertion/Origin/Action — blank skeleton and skull in which specified muscles are drawn/colored according to origin/insertion attachments; i.e., deltoid is drawn from deltoid tuberosity on humerus to clavicle on posterior view.
    • First few done on board in front of class to demonstrate just how each muscle should be drawn and information listed
    • Individually fill in worksheet; work in small group to look up/determine origin/insertion/action in class
  • String Lab — students, in pairs, attach one end of the string (i.e., the looped end) to the appropriate location of the insertion and take the other end to the origin. Pulling on the origin end, they simulate the movement/action of the muscle.
    • Collaborative work to ‘act out’ with purpose in class
    • Focus upon ten specific muscle actions
    • More clearly presents why a particular muscle produces a particular action

3. Contrast Skeletal, cardiac and smooth muscle in terms of structure and function

  • Flipped notes 6.2 — information on structure and function of three muscle types; detail of microscopic organization of skeletal muscle; neuromuscular junction (14:02)
    • Detailed differences between muscle types
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Muscle Tissue Flowchart
    • Reinforce structural differences

4. Describe the organization of skeletal muscle: (a) at the macroscopic level; (b) at the microscopic level

  • Flipped notes 6.2 — information on structure and function of three muscle types; detail of microscopic organization of skeletal muscle; neuromuscular junction (14:02)
    • Progress from fascia/periosteum to epimysium to myofilament, banding within the sarcomere, organization of thick/thin filaments, including SR and T-tubules.
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Anatomy/Physiology ColorPlates Packet — copies of relevant pages in the Anatomy and Physiology coloring books of microscopic anatomy
    • Anatomy is visual; this provides reinforcement of knowledge
    • Done individually as homework

5. Explain the key steps involved in the contraction of a skeletal muscle fiber: (a) discuss the physiological changes required to contract and relax a muscle fiber; (b) discuss the protein conformation changes necessary for contraction.

  • Flipped notes 6.2 — information on structure and function of three muscle types; detail of microscopic organization of skeletal muscle; neuromuscular junction (14:02)
    • Neuromuscular junction anatomy
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Flipped notes 6.3 — muscle physiology (33 slides)
    • Sliding filament theory, action potentials (electrochemical gradients, Na-K pump, graphing AP), and energy sources for contraction
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Physiology ColorPlates Packet — copies of relevant pages in the Physiology coloring book
    • Processes are visual; this provides reinforcement of knowledge
    • Done individually as homework
  • Sliding Filament Theory Video — students devise video to simplify changes in protein conformation into 4 steps
    • Point is to instruct peers; posted to website
    • small group project, done in class
  • PhET Neuron Simulation Lab — simulation of action potential and physiological changes responsible
    • Individual or group, in class or homework depending upon time
  • Rabbit Muscle Lab — teased sample of muscle receives different treatments, contraction observed under the microscope
    • differences in contraction noted
    • done in class, students work in pairs

6. Compare the different types of muscle contractions

  • Flipped notes 6.3 — muscle physiology (33 slides)
    • Sliding filament theory, action potentials (electrochemical gradients, Na-K pump, graphing AP), and energy sources for contraction
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Pushing the Limits: Strength video — animations of contraction, provides explanation of the power of the body and extremes of what the body can do
    • backchannel during video for comments and questions

7. Describe the mechanisms by which muscle obtains and uses energy to power contraction; distinguish between aerobic and anaerobic endurance

  • Flipped notes 6.3 — muscle physiology (33 slides)
    • Sliding filament theory, action potentials (electrochemical gradients, Na-K pump, graphing AP), and energy sources for contraction
    • Done individually; checked via flipped questions to identify any lingering misunderstanding and provide analytic of completion
  • Exercise & Cellular Respiration Lab — impact of exercise upon rate of carbon dioxide production
    • changes in carbon dioxide production noted as amount of exercise changes
    • done in class, students work in pairs
  • A Perfect Storm in the Operating Room — case study
    • interrupted case study on malignant hyperthermia
    • students answer packet questions and turn in a group report based on the last set of questions
    • small groups during class

Summary Activities

  • Disease Glog — a digital poster providing a ‘story’ about a disease
    • basic explanation about the disease, including appropriate statistics
    • explains what homeostatic imbalance is responsible for the disease
  • Blog Post — Muscular system, either or below
    • anatomy of muscle, explaining, with detail, the relationship between form and function within the system
    • physiology of muscle, linking to homeostasis for the body and how homeostasis maintained within each organ

Changes

First, it is glaringly obvious I must make changes to my videos — they need streamlined and topic/concept focused: just pics and labels for major muscles, just nomenclature, just origin/insertion, just sliding filament, just energy, etc., eliminating nice-to-know-but-not-essential items. Also, some just need to be slides, slide rocket would do the job. Some need to be augmented with Popcorn Maker: more interactivity, more quick quizzes (translation: low risk, formative assessment) during the notes for contraction and muscle energy. This would also create a more effective use of the JITT and ConcepTests ideas in my Anatomy class, allowing the recap/discussion the next day to address the issues identified during the notes.

Second, embrace the limited scope of some objectives. Looking at number 1, muscle function is basic knowledge. List it and move on. A similar change needs to occur with number 3, differences in cardiac, smooth and skeletal muscle. There’s a table in the textbook listing the differences between the tissue types; this is enough to address the objective. Simply point out the table and mention the Cardiovascular and Digestive systems will go into the depth of the specific muscle types, just like this system is used to present/discuss details of skeletal muscle.

Contraction differences, number 6, could be eliminated. As future chapters will go into greater detail for cardiac and smooth muscle and since I’m limiting the tissue differences to be presented, the only item left here is isotonic and isometric. This can be a component of context, posture vs. running for example, but does not require its own standard.

Thirdly, move in the direction of explore and develop curiosity (i.e., explore, flip, apply from flipteaching and Ramsey Musallam’s blog). This is where I’m weak.

My first thought is to make the “string lab” be the introductory activity. See if students can figure out where muscles must attach in order to produce known movements. Then, send the blank muscle man home to fill out as homework; check it first thing the next day. This would frame the nomenclature discussion. This also could lead into the microscopic anatomy: fascicle arrangement in names, leading to a review of micrographs, leading to a discussion of the structure behind the banding.

Another change is to keep the anatomy and physiology of contraction together – I’ve separated them the last couple of years. This separation hurt rather than helped this concept. The PhET lab would be done first, before even starting contraction, but right after the microscopic structure above. This sets the stage for the physiological/anatomical changes responsible for contraction.

The last concept is energy. I’m thinking the exercise cellular respiration lab should be done first. Then, the rabbit muscle lab. After the notes on energy sources/pathways, the case study. It becomes a summative application, requiring students to pull it all together.

All of these changes I hope will also make the disease glog and blog post more impactful. Allowing students to tell about one aspect of muscle function and the lack thereof.

My remaining questions: where to put in the videos? They are great stories and the backchannel during is always interesting, but is that enough to keep them? As for the color plates: limit to essentials, but should I have the students identify the essentials? Which means the students choose the muscles to know origin/insertion for, rather than me defining the list…good idea?

Should I eliminate more? Is there something I haven’t even thought of?

Please share any and all comments/suggestions. Thanks ahead of time.