DepEd's Spiral Curriculum II
Browsing through DepEd's curriculum guide for science, one can pick from the grade level standards elements that are related to chemistry:
Grade 3: Students will learn that things may be solid, liquid or gas while others may give off light, heat and sound.
Grade 4: After investigating, learners will identify materials that do not decay and use this knowledge to help minimize waste at home, school, and in the community. They will also investigate changes in the properties of materials when these are subjected to different conditions.
Grade 5: After investigating, learners will decide whether materials are safe and useful based on their properties. They will also infer that new materials may form when there are changes in properties. Learners will recognize that different materials react differently with heat, light, and sound. They will relate these abilities of materials to their specific uses.
Grade 6: Learners will recognize that when mixed together, materials do not form new ones thus these materials may be recovered using different separation techniques. Learners will also prepare useful mixtures such as food, drinks and herbal medicines.
Grade 7: Learners will recognize the system of classification of matter through semi-guided investigations but emphasizing fair testing.
Grade 8: Learners will explain the behavior of matter in terms of the particles it is made of. They will also recognize that ingredients in food and medical products are made up of these particles and are absorbed by the body in the form of ions.
Grade 9: Learners will explain how new materials are formed when atoms are rearranged. They will also recognize that a wide variety of useful compounds may arise from such rearrangements.
Grade 10: Learners will recognize the importance of controlling the conditions under which a phenomenon or reaction occurs. They will also recognize that cells and tissues of the human body are made up of water, a few kinds of ions, and biomolecules. These biomolecules may also be found in the food they eat.
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One of these differences is very important. The word "stoichiometry" cannot be found in DepEd's K to 12 curriculum guide. Tai, Ward and Sadler, in a study published in the Journal of Chemical Education ("High school chemistry content background of introductory college chemistry students and its association with college chemistry grades." J. Chem. Ed., 2006, 83(11), 1703-1711.), found that of all the topics that high school chemistry covers, only "stoichiometry" is found to be a good predictor of college chemistry performance. They arrived at this conclusion from a survey of more than 3000 students across the United States. The statistical analysis shows convincingly that performance in introductory courses in chemistry in college is strongly correlated with how well stoichiometry was covered in high school. And excerpts from individual responses from students provided a glimpse of the underlying reason behind this strong correlation:
I think stoichiometry gave a lot of kids trouble so I think my fairly strong background with that gave me a heads up.
...stoichiometry—I learned that really well in high school and I remembered it all throughout chemistry.
...knowledge about stoichiometry from high school chemistry helped me most.
I’d have to say stoichiometry because quite a few people had problems with that.”
...stoichiometry and the ability to apply conversions helped the most.
...most helpful was the depth [with which] we covered stoichiometry....
Stoichiometry ( /ˌstɔɪkiˈɒmɨtri/) is a branch of chemistry that deals with the relative quantities of reactants and products in chemical reactions. In a balanced chemical reaction, the relations among quantities of reactants and products typically form a ratio of whole numbers. For example, in a reaction that forms ammonia (NH3), exactly one molecule of nitrogen (N2) reacts with three molecules of hydrogen (H2) to produce two molecules of NH3:
- N2 + 3H2 → 2NH3
Stoichiometry can be used to find quantities such as the amount of products (in mass, moles, volume, etc.) that can be produced with given reactants and percent yield (the percentage of the given reactant that is made into the product). Stoichiometry calculations can predict how elements and components diluted in a standard solution react in experimental conditions. Stoichiometry is founded on the law of conservation of mass: the mass of the reactants equals the mass of the products.
When I was teaching chemistry to non science majors at the Ateneo, I used the assembly of bicycles to illustrate stoichiometry. I begin with the assumption that all bicycle parts are available except for the handles and tires. I then ask the class how many bicycles I could assemble if I had two handles and two pairs of tires and of course, everyone answers "two". Interestingly, when I change the initial conditions to having 5 pairs of tires and only one handle, the class got the correct answer as well, only one bicycle, because I was limited by the number of handles I have. This is stoichiometry. In a chemical reaction, a given ratio needs to be met by the starting materials. If this ratio is not met, there will be an excess in one of the starting materials while another will be totally used. Doing this in chemistry involves arithmetic since substances react with each other in units of either ions, atoms or molecules. Thus, to evaluate the stoichiometry of a given reaction, one must first know how to convert quantities that we are familiar with in the macroscopic world such as mass or volume into units that are appropriate for the microscopic world of atoms, ions and molecules. Stoichiometry is quantitative and for this reason, in high schools where only the descriptive or qualitative aspects of chemistry are emphasized, this topic is often neglected.
If stoichiometry is covered in college courses, why should its high school coverage have an effect on a student's performance especially when stoichiometry is only one of the more than two dozens of topics covered in an introductory course of chemistry in college? A college instructor should be able to address and teach stoichiometry. Herein lies one of the principles of basic education. Basic education not only teaches what to think, but also how to think. Basic education should make students think. And this is what students do when they perform calculations in stoichiometry. And if students fail to learn this in high school, they will have great difficulty not just in college, but in real life. We should not leave this important ingredient in chemistry education to the additional two years in high school. At that time, the two tracks are already in place. And not everyone will be taking chemistry as a subject.
DepEd's K to 12 chemistry fails to emphasize stoichiometry because it likewise neglects what chemistry is all about. Chemistry is founded on seeing the world through the eyes of atoms and molecules. Chemists see reactions in the following way:
|Examples of Lewis acid-base equilibria.|
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Stoichiometry is indeed important. It illustrates a way of thinking and an important fact of life. Both teacher groups, the Alliance of Concerned Teachers and the Teachers' Dignity Coalition probably have their own version of stoichiometry as applied to improving Philippine basic education:
Unfortunately, President Aquino's government does not even have any one of these ingredients....
Yup, gotta' love those drug ions. I am thinking these standards were written by someone whose chemistry endedReplyDelete
after qualitative analysis -- every chemical reaction is some kind of precipitation event.
I was told they were prepared by the leading experts in the Philippines - that is why I should just shut up. But you have to give credit to them - we love those drug ions!ReplyDelete
It seems to me that the K+12 curriculum developers consider the terms "decongested" and "watered-down" synonymous.ReplyDelete
In the Science K+12 Curriculum Guide, it is stated: "Rather than relying solely on textbooks, varied hands-on, minds-on, and hearts-on activities will be used to develop students’ interest and let them become active learners. "
Is this the reason why DepEd did not provide Grade 7 students with a science textbook that addresses the new content standards?
Are we to assume then that the modules that DepEd has developed will deliver the promised hands-on, minds-on and hearts-on learning?
With these modules, DepEd seems hellbent on dictating not only WHAT teachers should teach but also HOW and WHEN to teach them.