One of my goals this upcoming year is to step up my whole group math lessons. I know I have to teach place value and I know that's a tough concept for most kids to master. Usually we do a warm-up with them, not only to spiral skills they are learning, but also to try and keep them thinking. I see a lot of things like anchor charts that tell the kids the strategies they can use for addition and subtraction-one of them teachers list is counting on their fingers. I may be in the minority on this one, but I actually discourage that in my class. On a test, I tell them they can use anything they need to answer the question, but when we are doing these whole group activities-I want them to think about the answer first. There's no reason they should have to count on their fingers to add 1 to 5-and definitely shouldn't have to count that 5.
I will never forget tutoring a 4th grader for their big test years ago. The practice question was something like-Bob delivers 10 magazines a day for 5 days-how many magazines did he deliver? The student started counting on his fingers-1, 2, 3, 4, 5, 6....counted to 10 five times and got the answer of 49! I remember thinking to myself, I think my students would even count by 10's to reach that answer. These kiddos just aren't getting the practice in number sense that they really need to understand the math they are doing.
Here are some things I do to try and encourage a better understanding and I would love to hear your ideas on activities you use as well.
A quick little activity-I pass out foam dominoes and ask questions like-hold up your domino if your total is more than 5, or less than 6.
Mystery number-I have a number in my head and you have to ask me questions to narrow down what that number is. More than 50, less than 20, odd or even? I put this on the Smartboard and the students eventually run it themselves-one of the kiddos picks a number and fields questions from the students. My favorite part is watching them try to figure out things like if the question is more than 50-do I take away 50? Well, is 50 more than 50? And they discuss what they think with each other.
Real-world connections: Using photographs
How many gray planes? How many altogether? If the gray planes took off, how many are left? Pictures of castles or sailboats work well to review shapes-how many triangles/rectangles?
Buzz-my kids love this game!!! They form a circle and the one in the middle picks a number to be "buzzed". Any digit with that numeral in it cannot be said-instead they say buzz. So if the number is zero, when they count 8, 9 ,....buzz. You can make it harder by making it sums made from doubles or multiples of 5 as they progress.
This is a great way to start discussions about how they get to a certain number. How did you know it was 10-did you count 1+1+1, etc. or did you do 5 +5. Pretty soon they get pretty fluent and don't have to count the dots anymore.
What kind of review activities do you use to encourage mental math? I'd love to add to my toolbox! :)