Wood You Marry Me?-Weighty Wood

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Students will use a scale to compare and record the weight of different kinds of wood.

Big Idea

Can the same wood be different?


5 minutes

I ring my chime to get the class’s attention and ask them to return to the carpet squares and ‘Show Five’.  Once seated, I announce that we are about to begin the third Science lesson in our unit about wood.  This lesson is an extension of the previous lesson of the features of wood.  To engage them, I ask for two volunteers.  As they both stand in front of the class, I ask “Who can tell me which one is heavier?”  “It’s the one that’s taller.”  “How would we tell if that was true?”  “Umm..I don’t know.”   “We’re going to take some time to talk about one way that wood is different..and how we can test that difference.”  Brief illustrations like this, as simple as they are, can be valuable visual tools to encourage focus and direct attention on the lesson at hand.  With this, we are ready to move on.

Whole Group Instruction

10 minutes

During this unit, I find it useful to use a variety of books to illustrate the lesson concepts.  Each book has it’s own specialty that helps deepen the understanding, as well as present the material in a variety of reading levels.  For this lesson, I re-introduce another book titled Wood.  I review pages 6-9, highlighting the parts that refer to the ways wood can be different.

Remember when we studied the structure of trees?”  “I do!”  “Great!  Can anyone help me remember something?  I’m wondering what the hardest part of a tree is called?”  “Heartwood?”  “Oh, yeah!  You’re right.  It’s called ‘heartwood’.  That’s the hardest part of a tree.  Most of the time, the hardest part is also the heaviest because it’s what’s called dense, the fibers of the wood are closer together.”  I put my fingers together as a visual example. “They’re squished?”  “Exactly!  So today, we’re going to be botanists and measure which types of wood are the most dense.  What else will that tell us?”  “Which kinds are the strongest, right?”  “Right!  This tells people like carpenters the best purpose for the wood.  Some light wood that aren’t as strong make great frames.  Other woods that are heavier make good chairs, tables, and even boats.”  “What???  Boats are wood?”  “Of course.  There are many things made out of wood.  Each wood is chosen for its unique properties- things that are special about it.  This makes a product that serves it’s purpose.  Who’s ready to be botanist and help some carpenters choose the right wood?   “Me!...Of course!”

Small Group Instruction

10 minutes


• Wood Collection (8-10 sample varieties)

• Balance Scales (1/small group)

To make this lesson support a real life skill, I have the students use a variety of scales to weigh the wood. It’s a skill that can be applied to a variety of subjects so I’d like to use this opportunity for them to be able to see scales used in another application. “Hey, these are like the ones we use at the grocery store.”  “Exactly like thatWe are going to weigh wood the same way as you weigh food.”  I show them a collection of wood and explain the process: 

• First, choose two types of wood samples from the collection on the table.

• Next, write the names of the wood on the lines on the ‘Heavier or Lighter?’ paper.

• Then, put a piece of wood on each side of the scale.  Which side of the scale goes down?   

• Last, circle either ‘lighter’ or ‘heavier’ on the sheet to compare the two wood varieties. 

I watch and circulate as the children get together with their tables groups and go through the process to select, weight, and record the results of the woods. Essentially, the students learn the concept of judging relative weight fairly quickly so this section of the activity takes about five minutes, although it can go on as long as your class wants. As the activity winds down, I give them a one-minute warning with a hand-clap pattern. I ask the students to take their papers and return back to their carpet squares.

Wrap Up

5 minutes

Once we gather, I ask, “Take a minute to share your result with another group.”  To wrap it up as a group, I choose to make an informal list.  “Can anyone share which types of wood were heavier than others?”  “The oak was heavy.”  “So was the canary wood.”  “If we start to record the types of wood that are heavy and light, we’ll better know what kind to use when we want to begin our projects, right?”  “Right!”  I take a second to clarify the result, while supporting the process.  To address the learning, it’s important to include the application piece-what’s the purpose of this information?  It helps to think through the concept, while adding valuable language skills.  This step is short by design because the intent is to give the students an additional opportunity to process and share their results, thus making the material more concrete.  Once this initial presentation is complete, I again ring the chime to end the lesson.