I try to avoid having students memorize things, when possible. I think it is far more valuable to be able to figure something out from other information or to be able to read and write science or to be able to think through a stoichiometry problem. But when it comes to polyatomic ions, students just HAVE to memorize them. There is no way around it.
It’s sort of like multiplication facts in elementary school. When students are learning how to multiply, they can do a lot of different activities to teach them the logic behind multiplication. They can practice with manipulative and iPad app games and such. But in the end, each student HAS to memorize them because if they don’t, they will be unable to do multiplication problems in the future.
Polyatomic ions are the same way. When you arrive at the nomenclature and bonding units of your year, they must memorize the polyatomic ions. They will use their knowledge of the ions throughout the rest of the year in stoichiometry, acids and bases unit, equilibrium unit… They just need to memorize them. Using them in problems from day to day will help too, but really, they just have to sit down and do the memorization work!
Here are a few ideas to help students memorize the polyatomic ions and their charges:
1. Flash cards: I personally believe that for flash cards to be useful, students need to make them themselves. The active part of creating them is just as important as practicing with them. I have students put the name on the front and the formula on the back. Or formula on the front and Lewis structure on the back if we are covering Lewis structures!
2. Plain old Polyatomic ionic quiz that you tell them you’re giving! Give them a list of them, give them a few days to memorize them, and tell them you are going to test 10 of them. There is no partial credit. Just flat out right or wrong. I know it’s sort of old-fashioned, but this is what forced me back in the day to memorize them. I recommend if you do this that you pick a different (or even random) 10 for each class period, because you know friends share which ions are asked in their class period. Tell them it will be different for each class so they don’t even bother trying to cheat and talk between classes.
3. Make it a competition! You can do a quick-write on the board game where you ask your students. Make a stack of small cards so you can pick a name randomly. Have students form 2 or 3 teams (depending on how much chalkboard or whiteboard space you have) and have one student from each team go up at the same time. Pick a card, shout out just the name (like “CARBONATE!”) and students have to write the formula down as fast as they can (or the Lewis structure if you’re in a more advanced section.) Students love writing on the board and they love games. You could throw the winning team an extra credit point on the next test, candy, or just bragging rights!
SPECIAL NOTE: My rule when I do this type of game in biology or chemistry class is absolutely no throwing my whiteboard markers. Because if you do, you BUY me a new set. I always spent quite a bit of my own money on nice colorful Expo whiteboard markers and it drove me nuts if students got cocky or angry during the game and threw the markers.
(Nick, you still owe me some markers, if you’re reading this…! Yes, that was over 5 years ago. But a rule is a rule!)
4. Play BINGO! (Or “ATOMS”!) You can find it here in my TeachersPayTeachers store. I created a set of 30 unique bingo-style cards that students can use. I include versions with formulas and versions with names, so you can have students practice finding the formula from the name or the name from the formula. I even created custom markers for students to use on their sheets! I love printing these on colored paper to make it even more fun.
What’s your favorite tip for teaching polyatomic ions? Please add in a comment below!