Battle Lines
If you haven't yet, remember to check out my Holiday Gift Guide 2020! If you need a mathy gift for a kid of any age, you'll find something to enjoy there.
I'm always on the hunt for games that teach kids about the other areas of math aside from arithmetic. I can name two dozen games offhand that help kids with addition, subtraction, and multiplication, but some of the other areas of math, such as measurement, don't come up explicitly in games quite as often.
That's not to say that kids never measure in games: They do it all the time! But sometimes you want a game that helps kids think about measuring more explicitly.
Fortunately, my math teacher friend Kyle DeBoer has invented a fantastic measurement game. I took the game into my other math teacher friend, Rebecca Smith's 4th grade classroom at my son's school, and I can tell you that kids love this game!
It's called Battle Lines.
How to Play
To play Battle Lines, you need colored pencils, a ruler, a six-sided die, and a piece of poster board. I cut the poster board into long strips that were about 2 inches wide and drew a big line down the center in Sharpie.
That line is the game board. Each player starts by rolling a die - the person with the lower number goes first and marks off a segment of the line with their colored pencil. So if you roll a 3 and I roll a 5, you'll go first and shade a 3cm segment of the line. Then you label it with the number 3.
Then I roll and shade in a segment of that length anywhere on the line. We keep going back and forth, rolling the die and shading in segments. You can combine your new segment with an existing one, or draw a new segment somewhere else entirely. Play continues until someone rolls a number and cannot place a segment of that length on the line. At that point, the game is over.
The winner of the game is the person who has the longest continuous line segment of their color. Here's the catch though: Your longest segment must be precise! If you've made a 9cm segment by connecting a 4, 3, and 2 centimeter segment together, you might be the winner. But if that segment actually measures 10cm long, you've lost!
This scoring rule is important because it makes your kids attend to precision - they need to actually know how to use a ruler in order to draw a length accurately.
The game plays very quickly, so you can get a few rounds in within half an hour.
Where's the Math?
Battle Lines is pretty explicitly a math game, but it's worth discussing the particular elements of measurement that come up in the game (and the variations that I discuss below).
Most importantly. the game gives your child a reason to care about how rulers work. Yes, they probably learn in school how to measure, but without a motivating task, they might not engage with the ideas or retain them later.
And measuring with a ruler is trickier than you might think! Check out this classic "broken ruler" problem. How long is the pencil? Some kids say 11 units because that's the highest number they see. Other kids say 7 units because they count the 5, 6, 7, 8, 9, 10, and 11, which is a total of seven numbers.
You can help your kids work on this specific topic with one simple additional rule: Any segment you draw must be at least 1cm away from your opponent's segments.
When I introduced this rule in Ms. Smith's class, the students immediately discovered a new trick with their ruler. If they wanted to draw a 5 centimeter segment next to their opponent's segment, they'd place the 0 at the end of their opponent's segment and then draw their own segment from the 1cm mark to the 6cm mark. A couple of rounds of this and your kids will have no problem with this broken ruler problems!
The game also gives your kids a concrete experience with specific measurements, which will build their ability to estimate shorty lengths. This is especially true if you use inches, although you may want to extend the playing surface if you use larger units. Perhaps a line drawn down the driveway in chalk could work better for inches!
Here's another variation I've considered but haven't yet attempted: Play on a circle instead of a line. Instead of shading in segments, you shade in sectors of the circle. So if you roll a 1, you shade in a 10° sector, if you roll a 2 you shade in 20° and so on.
In any case, this is a game that has a lot of promise in my opinion. But it's also not in its final form; I can feel that there are a lot of parents and teachers out there who could add interesting rules, twists, and variations. So try it out and send me an email back with your thoughts! Kyle and I are very curious.