How Old is This Class? Try Giving Students "The Silent Treatment!"

 Hi All,

Have you noticed those ads where a business says something like, "We have over 25 years of combined experience fixing cars!" Most often they are adding up the number of years of experience of each principal employee. So if there's two people who are fixing cars in a garage and 1 has 12 years of experience and 1 has 14 years, that's over 25 years experience" and I would feel pretty good about them fixing my car. 

However, if a different garage has 13 mechanics and each has 2 years of experience that also translates to "over 25 years experience," and though the advertising would still be technically true, I'm not feeling as comfortable bringing my car there.

Anyway, adding years up can be fun for kids and they are very aware of people's ages, which brings us to the problem/question: How many years of "combined experience" does your class have?

A good way to do this with younger kids is to give each student a blank double ten frame (like the ones at the link here) and some crayons. https://drive.google.com/file/d/1L01WIC3hj2_h6gbtSQ4Fr46wz3wdqsYd/view?usp=sharing

Ask the question, "How old is this class? I know you are all about 7 or 8 years old, but what if we were to add up all of your ages? How old would the class be all together? Let's find out."

Ask each student to color in the number of squares that would represent their age (7 years old = 7 colored squares) and to cut them out. Most students will end up with a train or rod of 5 plus another smaller train. Then have students sit on the floor in a large circle, each with their "train" or "rod" of colored squares in front of them. If you'd rather use unifix cubes or multilink cubes instead of cut-out paper squares, that works too

Sometimes as teachers we say too much. We want to help students get to an answer quickly and efficiently and we provide our own good strategies and answers rather than letting them discover these ideas themselves. "Solving Silently" or "The Silent Treatment" is an interesting approach to try now and then. 

Tell students, "We will go around the circle and each person will take a turn. When it is your turn you may move your train or anyone else's in a way you think will help us to solve this problem. Remember, we want to find a good way to count up how many years we have all together. You may only move one train on your turn."

Try to leave the directions at that other than to indicate whose turn it is. Given enough time, students will usually arrange the trains in fives or tens and this is a good strategy. Check out the two photos below. 

The first shows 7 + 8 right next to each other. Not so easy at a glance to add them up. With a simple movement breaking into fives and tens groups in the second photo, the answer is a quick, easy count away.

Because it is completely quiet and there are manipulatives involved, students are usually highly engaged.

After movement has stopped ask students to give a thumbs-up if they feel they know how many cubes there are all together. Have them whisper the answer to the person to their right. Ask if everyone agrees. Now discuss. Ask, "Can anyone tell me the answer and how this was solved?"

You can do this same activity any time you are adding together multiple addends. The "Silent Treatment" can work with any math activity. Try it and see!

Best,

Bob