Backyard baseball math takes a beloved sport and what for some is a dry school subject, and provides an inventive way to explore math during the summer months while also discovering a new way to fall in love with our national pastime.

For over a century, baseball players were judged by relatively few statistics: Batting Average, Home Runs, and RBI (runs batted in). Produce a stat line of .300/35/100 in those three categories and you’d likely be awarded with a massive multi-year and multi-million dollar contract. But baseball has changed dramatically during the past two decades, with more data being collected to better gauge the real effectiveness of players.

While newer statistics like On Base Percentage are more commonplace now in the professional game, your little slugger doesn’t need a Major League Baseball contract to know how his OBP is calculated or to take pride in her slugging percentage. Playing backyard baseball math is a simple way to have fun with advanced baseball stats, commonly referred to as sabermetrics, in the backyard with your kids and help to keep their bodies fit and their minds sharp before school starts again it the fall.

### What You’ll Need

• a grassy open space
• all-purpose flour
• baseball or Wiffle ball bat
• baseballs
• notebook
• pencil

### How to Prepare

Because you probably don’t have a baseball diamond in your yard, you’ll need to denote ‘zones’ for singles, doubles, triples and home runs. For this task, all-purpose flower from your pantry will do the trick. Simple pour the flour into four arches, like a WiFi symbol, with roughly ten paces between each (as space allows in your yard). Cones will work too, but aren’t nearly as much fun as pouring flour onto your lawn!

### How to Play

Have your kids hit off a tee or pitch to them as you would normally, but this time keep track of their hits, ‘strike outs’, and ‘walks’ on a notepad over, say 50 “plate appearances”. *Remember that walks and hit by pitches do not count as official at bats but are official plate appearances. Let’s discuss this further!

### Time to get Math-y

Baseball stats, even the fancy new ones, are nothing but math problems at their core and usually, they are fairly simple math problems too!

Let’s calculate On Base Percentage (OBP) first using this formula:

(Hits + Walks + Hit by Pitch) / (At Bats + Walks + Hit by Pitch + Sacrifice Flies)

For example, from a set of 50 plate appearances let’s say your child managed 12 hits and that you walked her 6 times and accidentally hit her twice:

(12 Hits + 6 Walks + 2 Hit by Pitch) / (42 At Bats + 6 Walks + 2 Hit by Pitch) = .400 OBP

A remarkable figure because the higher the OBP, the better the player is believed to be. Mike Trout, for example, a player many believe is the best hitter in baseball today, had an OBP of .399 in 2012 and .432 in 2013.

Now, let’s calculate Slugging Percentage (SLG) with this basic formula:

Total Bases / At Bats

Using those same 12 hits over those same 50 plate appearances, let’s assume your child had 5 singles, 3 doubles (x 2), 1 triple (x 3) and 3 home runs (x 4) for 26 total bases, so:

26 Total Bases / 42 At Bats (remember that walks + hit by pitches do not count as official at bats) = .619 Slugging

Again, the higher the number the better so again let’s compare with Mike Trout. The Angels outfielder had a slugging % of .557 and .606 the last two years. Clearly, your kiddo is on their way to the Hall of Fame with those statistics!

Since you have OPS and SLG already calculated, just add them together and you’ll have your child’s OPS. Wow, a whopping 1.019 using the examples above! Time to call an agent, parents — your child is a superstar!

### Wrapping Up

Of course there were no fielders in your backyard baseball game, so no defensive shifts to counteract your right handed son’s propensity for pulling the ball down the left field line, but no matter! You’ve been outdoors, playing America’s game with your child, and then you both had fun with math and statistics back inside over a cool glass of lemonade.

### Bonus Tip

Take this backyard baseball math activity to a new level of fun by buying a few packs of baseball cards to compare your child’s stats to those of their summertime heroes!

### Download a Free Episode

Whether you’re at home or on the road this summer, PBS KIDS can be your partner in on-the-go learning. With our award-winning mobile apps (including the PBS KIDS video player) and PBS KIDS video available for download you can ensure your kids will have a trusty educational travel companion all summer long. Stop by our PBS KIDS Raising Readers home at iTunes and download a free episode this week! This week’s free episode is Peg + Cat: The Birthday Cake Problem/The Doohickey Problem.

### About Jeff Bogle

Jeff Bogle is an at-home dad who writes humorously about parenting and All Things Childhood on his site Out With The Kids. He is married to an adorable redheaded gal and has two lovely little ladies 12 and under who provide him with countless hours of humorous in-home entertainment, and who get to hear, see, and play with more cool stuff than you can possibly imagine.