### Purpose

To develop an understanding of the steps involved in designing structures.

### Context

This is a single lesson that is devised to enable students to create, design, and evaluate different structures. Students will use Lego blocks to create several different designs. They will evaluate the various steps involved in creating their structures. They will think about possible alternative steps for building their structures.

The evaluation process is an important concept for early education because students do not appear to understand what evaluation of design is or why it is important. (*Benchmarks for Science Literacy*, p. 349) Students also have trouble assessing and applying knowledge from other contexts while engaging in design and technology activities. (*Benchmarks for Science Literacy*,p. 349)

Because students like to build with many different types of materials, doing this activity with different types of materials will make it easier for them to become involved in the process of application and evaluation. After students have mastered the design of simple objects, they should move on to designing, assembling, and operating more complex systems.

### Planning Ahead

It is important that the blocks be bundled and prepared in advance so that student groups get the same number and type of blocks.

### Motivation

Set out several bagged sets of standard Lego blocks in advance. Make sure that each of the bags contain equal numbers of the different sized blocks (single-, double-, four-, and eight-peg blocks.)

Divide students into groups of three to four. Tell them to create a structure that uses all of the blocks. Allow students 5-10 minutes to work as a group on their structures. As a whole class, share and discuss group structures.

Ask students:

- How are your structures alike? How are they different?
- Which blocks did you use for a base? Which were used for the middle?
- How many steps did it take for you to make your structure?
- Did you change the structure at all? How?
- Did all of you contribute to the building and design process?

### Development

Tell students that they are going to complete some design challenges using their Lego blocks. Start by having students build the tallest structures they are able.

Ask students:

- Which blocks did you use for the base?
- How did you decide which blocks to use?
- Did you determine this by trying it or talking about it?
- How many times did you have to rebuild your structure?

Now have the students design the widest structures they are able.

Ask students:

- How did you determine the design of this structure?
- Which blocks did you use for the base? middle?
- How many times did you have to rebuild your structure?
- Is this a strong structure? How do you know? How did you test it?
- Could you redesign it to make it stronger?

Next, have students build structures that are able to bridge over a three-inch length. Allow students 5-10 minutes to make their structures.

Ask students:

- How many steps did it take to make this structure?
- How was the design of this different than the others?
- How was the design similar?
- Which blocks did you use for the base?
- Which blocks were used for the middle?
- How did your group decide on the design of your structure?

Have your students repeat this whole process using Tinker Toys. Use the questions that are listed above for each of the three different designs. Once students have completed building the structures using Tinker Toys, ask students:

- Were there more steps involved in building the Tinker Toy structures than the Lego blocks?
- How were they different?
- How were they similar?
- Which blocks were best to build a tall structure? Why?
- Which blocks were best to build a wide structure? Why?
- Which blocks were best to build a bridging structure? Why?

### Assessment

Say to students, *"Today, we looked at different types of structures and the steps it took to build them. Now your group is going to take a challenge. You are going to each be given 30 drinking straws and a small amount of clay. Your challenge is to build the tallest and the strongest bridge you are able. We will test the strength of your bridge by putting on a stack of 20 pennies."*

Allow the students 15-20 minutes to complete their bridges. When completed, test each group's bridge for strength.

Ask students:

- Why did you design the bridge this way?
- How many times did your group have to begin over?
- What steps did your group take to design this bridge?
- Was your bridge able to hold the weight of the pennies?
- If it was not, what do you think you need to change in your design?
- What did other groups do with their designs that worked well in this challenge?

### Extensions

Have your students bring in a list of instructions.

Ask students:

- How many instructions are on your list?
- Why do instructions usually have more than one step?
- What do instructions help to do?
- s it important that instructions give clear steps? Why?

Have student groups write the instructions for making a peanut butter and jelly sandwich. Have each group give its instructions to another group and then try to make a sandwich using only the instructions they are provided.

Ask students:

- Was there more than one step involved in making the sandwich?
- Are any of the steps unclear?
- Are there any steps that were left out in the instructions?
- How could the steps be changed to make them better?