WEEK FOUR

 

Liberato Cardellini

 

The number of students is 63: some are from the previous years.

I started every lesson in this week collecting the problems solved as homework, the filled questionnaire and the concept maps.  Then, I read the results of the correction of the problems, name by name looking for the students and looking at her/his eyes, telling the errors, the good things found in some solutions, commenting about the few that reported the time spent on the task, etc.  I emphasized the fact that two students correct themselves while solved the problem.

After every lesson, I correct the homework, then I send them a message telling them the number of solutions that I have corrected, some advice, the material I have explained and I also suggest them the problems to be solved.

In the week I received 26 e-mails. three was from sick students.  They asked the content of the lesson, what they have to study and the problems as homework.  Others sent the questionnaire, asked explanations about how to solve problems, asked if they have solved correctly their problems, etc.

 

Comments.  Some students that till now have marginally take part to the game, start to work seriously.  This happens not because I learned their names and start to call them by name, but for sure the human element play a role.  In the first week I tried to get them engaged by using some logical problems and set an high standard.  But I was able to engage only a few of them.

 

Monday 27 (1.5 h)

The students solved again in groups three problems they have already solved and I corrected on Monday of the second week (What is the mass of sodium carbonate that contains the mass of oxygen equal to 2.44x1022 molecules? and other two). I wrote at the backboard the results: from 0.something to 5 hundreds something included the result, 2.86 g. I called at the backboard a student, inviting he/she to write and comment the solution.  Then we discuss with the class, looking for the errors.  It results that many students do not yet use stoichiometric relationship, even if in the past lessons I had asked them several times to use them.

Some students said that they find difficult to balance redox reactions we balanced, because some students find the balancing still so difficult, till the end of the lesson.

 

I have collected 29 concept maps.  I have corrected 343 problems finding 13 wrong solutions and results.

 

Thursday 30 (3 h)

While correcting the problems, I realized that my students have trouble with average molecular weight.  So I asked a student to go to the blackboard and explain what she have understood about the average molecular weight, using an example.  As an introduction to the topic of the concentration of solutions, I asked the class to solve a neutralization problem, with the density involved.  Because I know that this problem is particularly difficult, I asked them to explain and argue every step of the solution.  After a break I asked another student to go to the blackboard and explain percentage, molar fraction, molarity, and molality.  The explanation was successful, because the student was in a previous course three years ago and failed the exam.

One of the tasks as homework was to solve the problem: 10.00 g of Na2CO3 react with 10.00 g of HCl.  Calculate the grams of the products and find a way to verify the result.

 

A student calculate the mols of reactant, considering 10.00 g of Na2CO3 and 20.00 g of HCl.  An oversight in reading the data?  No !!  This error comes from the confusion between what Mansoor Niaz call the general figurative model and the specific operative model.  Because the coefficient of HCl is two, the quantity of HCl become 20.00 grams.  Consistently the students find that the quantity of products formed was 25.48 g and concluded that cannot be correct, because the result is not 30.00 g!

 

As in the previous week, I talked with students that give me few problems solved or few CMaps.  I sent the a personal message too, inviting the student to start to work seriously for her/his qualifications: the written exam is approaching.  The strategy works: I received few messages with promises and solutions to problems and CMaps.  It seems that more I learn their surname, more those students get engaged !

In the message to the class I attached the text of the same problem they solved in groups about the density, asking them to explain every step in the solution.  This because I know that in this way they can correct themselves.

 

I have collected 12 concept maps.  I have corrected 289 problems finding 28 wrong solutions and results.  Another student solved Problem 5 in an original way.  Many students still do not verify their result nor report the time spent on the task.

 

Friday 31. (3 h)

It was an ordinary lesson about the solutions.  It was about questions to students, asking them to work in the groups to predict certain facts, properties.  They have no accurate idea about what happen in the distillation of a solution and on other facts.  But in this way they are engaged.

Students give me 9 concept maps and many solutions.  I corrected 210 problems finding 13 wrong solutions.  Students mistake the solutions because they do not verify the result.

 

I am aware that I ask a lot to my students.  This because I am convinced that a general problem of the western society is that we have lose the flavour to work for an important goal.  So it is difficult to work on the weekend, to live without the television every night and so on.  I try to remember my students that what can make the difference in their life is to have enthusiasm for something.  And this week other joined the group of very serious students, that enjoy to work regularly.

 

Asking my students a lot, am I doing the right thing?

 

A window in my office.

Pile of solutions: 1,777 from the Third week + 842 = 2,619.