Visualizing a Balanced Equation

If I was going to make a list of the 5 things I would want any student to be able to do when they leave high school chemistry, I would certainly include balancing equations on that list. A balanced equation is a chemical sentence, the shorthand way we have of representing what substances combine and what they change into. The equation has to be balanced (coefficients are placed in front of symbols and formulas) to show that the process obeys the Law of Conservation of Mass (all the atoms from the beginning of the process must still be around at the end). In December my students learned to balance equations and by the test before vacation, they had mastered it.

In an effort to make all this invisible chemistry more visual, I routinely ask my students to draw atoms and molecules using a model of different sized and colored circles to represent different types of atoms. Sometimes I provide the pictures and they interpret them; other times I provide the chemistry and they illustrate. On the test I gave before vacation, I asked them to draw the particles involved in this equation:

2 Al + 3 CuCl2 --> 2 AlCl3 + 3 Cu

Here are some of the responses:

What the student below drew would be Al2 + Cu3Cl6 --> Al2Cl6 + Cu3. The equation balances. All of the atoms from the reactants are still present as products. The coefficients and subscripts are confused, though, showing a lack of understanding of what those numbers represent. I love that the student included a key!

What this next student drew would be represented as Al2 + Cu3Cl2 --> Al2Cl3 + Cu3. Again there is confusion between coefficients and subscripts, but, in addition, this answer shows a lack of understanding that the coefficient applies to everything in a formula that follows it. 3 CuCl2 would not be molecules made of 3 copper (Cu) atoms and 2 chlorine (Cl) atoms. Also mass is not conserved here; there are 7 reactant atoms but 8 product atoms.

Most of the students drew something that looked like this next picture (or the one at the top of this post). This is the correct representation.

At the beginning of this year, I wrote about a new take on notetaking (my most popular post ever) and my experiments with sketchnoting. This visualizing chemistry is sort of an outgrowth of that and some other things I have tried over the years. Most of my students could balance the above equation in fewer than 30 seconds, but some of them, despite showing the ability to balance cannot correctly interpret what the equation means. And that is something I would never have known except that I asked them to draw it.

If you are teaching chemistry, asking your students to draw some things might reveal some misconceptions too. If you are not teaching chemistry, what could you ask your students to draw to check for understanding?

Nature at its Finest

I recently spent more time, in a busy holiday season, than I care to admit playing with an app called Toca Nature. Toca Nature is one of 29 apps designed by TocaBoca, one of my favorite app makers. I think I grabbed it when it was free for 24 hours earlier this month and the cute fox icon was calling my name on Sunday morning when I should have been doing almost anything else. After just a few minutes, I was hooked.

Open the app and you find an almost blank canvas. There is a square landscape and some trees to get you started. Like all of TocaBoca's apps, the graphics are great. They have just the right mix of realism and fantasy, if that makes any sense. With some simple controls, you can add trees of 5 varieties or add mountains or water. Or, if you're that kind of person, use the hatchet to chop things down. With the trees come some animals. The animals need to eat, so you collect food too. Use a magnifier to zoom in and see the animals up close. If it sounds lovely, it is. If it sounds lame, just try it. I think you'll get hooked.

I like a lot of things about this app. First, it gives kids - even very small kids - an inkling about ecosystems. If you chop down all the trees, the animals disappear. If there are no fish for the foxes to eat, they start to look pretty sad. It isn't grim; there isn't death and destruction. But as my son chopped down trees and the animals vanished, we all understood what was happening.  Second, it offers a chance for discovery learning in a way that can't really be replicated by children in the world. While TocaBoca makes the point that this app isn't a substitute for actual nature, it is also really cool that you can make these big changes - create a forest, grow mountain range - and see what happens. Also, there are five animals that come with the 5 types of trees, but others are also possible and you have to figure out how to bring them around. Part of what had me hooked was trying to figure out how to "make" a wolf. Third, the animals adapt. Put a fox or a bear in the snowy mountains and see what happens. It's awesome. Finally, the simplicity of the controls and the groovy graphics really draw the player in and make it an engaging experience.

I like a lot of things about TocaBoca too. I like that they make the point that their apps are designed for open-ended fun that isn't competitive or designed for a specific gender or includes in-app purchases. I like that they post information about the importance of learning through play, that they take the position that digital toys and physical toys can be played in concert with one another, that balance is important. And I like that they are designing interesting apps that respect kids and offer them, in many cases, an experience that would be difficult to have in everyday life. Until Nature, my favorite TocaBoca app was TocaBuilders, a very cool maker-style app that I have called Minecraft without zombies, but the next one I want to try is TocaBlocks. It looks awesome too.

If you just bought an iPad for your family or your child, check out the suite of apps by TocaBoca and put Toca Nature on the top of your list.

Create an Hour of Code this Week

This week is Computer Science Education Week. In conjunction with the week, and to encourage more people to try their hand at coding, Hadi Partovi and his army of friendly coders are encouraging us to create an Hour of Code. Two years ago this effort began and it grows every year. You don't need any experience to try your hand at some basic coding. The internet is crawling with easy activities and tutorials. In fact, Google's Made with Code has a fun Santa Tracker that is easy peazy. It won't take you an hour, but it might whet your appetite for more coding fun.


Two years ago I signed up to create an Hour of Code with my students. I blogged about it here. This year, like the previous two years, I will teach my students to write programs on their graphing calculators. I will lead them through one and let them create a second with only one requirement: the program must be used to solve a chemistry problem. I am always amazed at what they come up with. And how quickly they can do it after seeing just one program written.

If that sounds too high tech for you, try out one of these other resources:

• Made with Code Santa Tracker

• Lots of tutorials (Frozen, Star Wars, Minecraft, Artist, and more) at code.org

• Free classes at the Apple Store this week

• Cool iOS apps for coding: Tynker, Kodable, LightBot, Hopscotch, Move the Turtle, Daisy the Dinosaur

• Create stories, games, and animations with Scratch

• Learn to design video games with Gamestar Mechanic

• No tech? No problem. Learn the principles of coding with offline activities

There is something on this list for all ages, from about age 6 on. 

No one thinks that completing an Hour of Code with make someone an expert. But the idea that every student should have access to computer science education is a noble one. I have seen first hand in my classroom that, for some students, seeing that they can write a program is transformative. Spark someone's imagination this week by helping them create an Hour of Code. You'll be glad you did. And so will they.