Lesson Plan Industry Sector
Agriculture & Natural Resources

## Calculating Board Feet

### Lesson Plan Overview / Details

In this lesson students will learn how to calculate the volume of lumber using the board foot equation.

### Lesson Time

Instructional Time
1 Hour

### Objectives and Goals

• Students will accurately measure lumber length, width, and thickness.
• Students will successfully calculate the volume of each board sample.
• Students will determine the board feet calculation for four samples of lumber.

### Activities in this Lesson

• Need a 2 Foot Board - Hooks / Set

Have laid out in class several boards that all measure 2 board feet.(See Handout for examples)  Begin class like an episode of a home improvement show, "Extreme Makeover Home Edition".  Say someting like "We are ready for the big reveal of the house for the Smith family, I just have one small part of the special project I have been working on all week before we can MOVE THAT BUS! I need two board feet to complete the project." (For this demo I have a small project that is missing a piece that measures 2 feet in length.  The project can be someting simple like a chair or step stool) I have a twenty dollar bill (waiving the bill in the air) for any of you that can give me the right piece of material. (None of the boards will match the need of the project but they will all be 2 Board Feet in Measurement.) Select boards from the students and check to see if any of them fit the two foot need. Then explain that all the boards do actually measure 2 board feet and the difference between board feet and linear measurement. Thus unfortunately no one will get the cash!

• Measurement of Samples - Demo / Modeling

Using a tape measure show the students how to measure the dimensions of the pieces of lumber. Be sure to explain that we need three measurements to find the volume of our project: length in inches, width in inches, height in inches.

• Wood Sample Measurements [ Download ] This is a simple drawing you can use for students to record their measurements.
• Instruct the students to measure all of the samples set on the tables around the room or shop. Give them the handout to record their measurements and allow them 10 minutes to get the samples measured.

• Now that the students have three dimensions for all of the lumber samples, write the board foot equation on the board.

Wood is sold by the board foot at the unfinished stage in production. Most of the lumber we buy at the lumber yard is finished and therefore is sold by its nominal measurement ie, 2x4, and its linear dimension, commonly 6, 8, 10, 12, 16 foot sections. Unfinished lumber is sold by volume, called a BOARD FOOT. One board foot is equal to one cubic foot. To find the volume of anything we need to know three of its dimensions. We have just measured the samples around the room and now have Thickness, Length, and Width of all the samples. One Board Foot is the board that is 1" thick x 12" wide x 12" long divided by 144. To get from cubic inches which is what T" x W" x L" will give us, we divide by 144 and the finished units will be in board feet.

• Have students calculate the board feet of all the board samples that they have already measured.

• Board Foot Worksheet [ Download ] This is the same worksheet as the students used earlier to record their measurements. It has the board foot equation inserted with spaces to fill in the measurements, and then a blank for the answer they find with each sample.
• Larger Lumber - Lecture

This equation we have just learned works great for small pieces of materials, but if we are to measure some larger pieces, what might we want to do to make the equation easier to use? (wait for student response then guide them to) we would want to measure the length in feet. This changes the equation a little. We then need to use this equation BF= T" x W" x L' divided by 12 instead of 144, this will ensure that our units are correct.

• Equation for Larger Lumber Length in Feet [ Download ] Slide that displays the equation with the length dimension in feet, used for larger pieces of lumber.

### Assessment

Assessment Types: