1.10 Writing the Lab Report

Context:

In the introductory unit, I choose to closely guide the writing process for the lab report, and I have chosen to wait until after the constant velocity model has been well-developed and applied in a few contexts. Hence, prior to what I feel is a natural breaking point (the introduction of velocity graphs and motion maps) I have inserted what is a two or three day guided lab writeup process, with students actually creating the lab report on laptops in class. Lots of direct instruction in using Excel happens in these class periods. I introduce the concept of correlation, and show lots of "just in time" tips and tricks for creating lab reports quickly from an Excel spreadsheet.

Sequencing Rationale: It is important to me that students have had the opportunity to see the lab paradigm formalized into an early-stage model before attempting the lab writeup. If I send students off to write the lab immediately following the experiment, my experiece has been that their interpretion of its implications are quite weak, particularly in the first unit of a semester with me. If we wait until the end of the unit, the lab writeup becomes almost drudgery and repetition of concepts they have already mastered. Placed mid-unit, I feel it's a great way to build comprehension around the model through the writing process...it's more in the ZPD, if you will.

Objectives:

• Students will learn to use MS Excel to transfer the graphs they originally created by hand into a digital format.
• Students will use interlinked language, graphs, and equations to describe the relationships discovered in the constant velocity vehicle lab. In particular, students will gain exposure to academic language in making physical interpretation of a graph of physical data.
• The slope, intercept, sign of slope, linearity, and correlation all have significance here. With and teacher modeling, students will begin to develop written fluency with these quantitative concepts.

Mini-Lessons:

Teaching computer skills is a delicate dance, as the class will not move as a single group, and it is important to insert mini-lessons in such a way that you pull the class forward and do not leave the advanced students to browse their favorite social networking site. Better to move too fast than too slow, however. Chunk your skill-teaching so that it fits with a "just in time" approach. When it is time to copy and paste the data table, teach them how...etc. Don't try to teach it all up front, and give all the minutae of features...just what is needed at the moment.

I chunked my mini-lessons like this:

1) Open up word and excel

2) Create an outline lab report in word

3) Enter data for each car in its own spreadsheet, with the independent (time) on the left and the dependent (position) on the right.

4) Format numbers to reflect the actual precision of measurements.

5) Use the chart wizard to create an XY scatter plot, with simple points (no connector lines)

6) Use appropriate title and axes labels.

7) Add trendline, set intercept (if appropriate)

8) Introduce correlation (see attached resource sheet)

9) Show how to edit trendline to add correlation

10) Verbally interpret equation given by excel....interpret correlation. Understand that units of slope are implicit, and not given by excel.

11) Copy and paste data tables

12) Format data tables to show grid

13) Copy and paste graphs

14) Model academic language for "data evaluation" and "conclusion" sections.

15) Use Powerpoint drawing features to quickly and simply sketch apparatus, group objects, and paste into word. (be careful with letting kids use sophisticated computer drawing tools in their lab reports...they will obsess over it, missing the point of the report)

Delivery of computer skills instruction: Most of these were delivered as I sensed the room was ready...in five minute bursts, in which I spoke quickly, deliberately, using an LCD projector to model, and reminded students to pause and look up, so they could get a sense of what was ahead. I reassured them that I would repeat if necessary, but always kept myself 2 to 3 minutes ahead of the students in my model on the screen. I found this approach kept them all really productive and focused...

Teaching students how to interpret graphs and equations. With students who have had little prior exposure to the academic language of quantitative analysis, simply instructing students to "interpret the physical meanings of slope and intercept" and "derive the equation, in terms of the experimental variables, of the relationship" simply won't produce results or comprehension.

This time, I gave reluctant students "starter sentences" that use the language and grammar of quantitative analysis.

"Looking at the graphs for car A and B, we can see that..."

"The slope of the best fit line is _____ (don't forget units) which means that ..."

"In this case, the sign of the slope is ______, which implies that..."

"Looking at the intercept, whose value is _____ (don't forget units) which tells us that..."

"The fact that the data falls almost perfectly (give R2 value) along a straight line suggests that..."

"Comparing the two graphs, we can see that....which means that..."

"Using 'x' to represent position and 't' to represent time, the equation that represents the motion of car A is ___________"

"Using 'xo' to represent starting position, and 'v' to represent velocity, the GENERAL equation for the position of object that moves at a constant velocity is ...."

For our first lab, this method seems to have dealt with a great deal of the anxiety and uncertainty that students feel around the vague task of "data evaluation

I also led the students through a sample derivation of the equation from Excel. The ideas here is to get them comfortable with:

1) Excel doesn't do units, so you have to figure them out for yourself.

2) Excel doesn't know what your variables are called. It uses y and x, so you have to convert the equation by substituting the variable labels you want to use.

I realize that this may be much more teacher-directed than many 'modelers' may advise, however I am working with a wide range of ages and abilities in the same room, some of whom have never seen a linear equation, so my experience with a more student-centered lab writing process has been that the first round of lab reports do not come anywhere close to meeting standards, if I get them at all. Students are hugely intimidated by writing lab reports...so this is a way for me to demistify the process a bit, so I can get more independence from them on later labs.