The holiday season is here! Time to get festive by building our own “gingerbread” houses and trees, and lighting them up!

This week, we will explore some engineering techniques and challenges, as well as deepening our understanding of the science of circuits, all in the context of creating a wintery town.

Activity 1: “Gingerbread” Houses Activity 2: Cardstock Christmas Trees Activity 3: Adding Parallel Circuits
Materials
  • At least 6 small sheets of cardboard per student (preferably 10 each)
  • Glue sticks
  • Scissors
  • X-Acto knives/ box cutters (for adult use only)
  • Cutting mat
  • Tape
  • Hot glue
  • Cardstock
  • Rulers
  • Writing implements
  • Decorative materials like tissue paper, pompoms, cotton balls, winter sequins, etc.
  • 2 sheets of green cardstock per student
  • 4 craft sticks per student
  • Scissors
  • Glue
  • Tape
  • Coloring implements
  • Decorative materials like pompoms, cotton balls, sequins, etc.
  • LEDs, at least 2 per student
  • CR 2032 3V coin cell batteries, 1-2 per student
  • Copper tape
  • Binder clips
  • Paper/cardstock (optional)
  • Pencils
Lesson Flow
  1. Gather materials
  2. Introduce the topic
  3. Show example photos of different cardboard connecting techniques
  4. Have students build a “gingerbread” house/ other building out of cardboard sheets, connecting them with one of the techniques
  5. Decorate the houses!
  1. Gather materials
  2. Introduce the challenge: Build a freestanding Christmas tree out of cardstock and craft sticks
  3. Show example pictures, but have no physical examples
  4. Let the students build their trees
  5. Decorate the trees!
  1. Gather materials
  2. Remind students about circuits and introduce parallel circuits
  3. Have students draw where they’ll put their circuits
  4. Help them build their circuits, perhaps on their house or tree
Goals
  • Explore the design process
  • Fulfill criteria while staying within constraints
  • Practice different cardboard attachment methods
  • Explore the design process
  • Fulfill criteria while staying within constraints
  • Creative, out-of-the-box thinking
  • Reinforce the basics of circuitry
  • Learn how to build parallel circuits
  • Design thinking/ creativity

Lesson Steps

  1. Introduce the topic: “Today we’re going to build gingerbread houses. But since real gingerbread and candy are messy, we’re going to use cardboard instead!” Hand at least 6 sheets of cardboard to each student.
  2. Before the students connect their walls together, use an X-Acto Knife or box cutter to help students make any windows or doors. They should draw where they want you to cut.
  3. Introduce the challenge: “To make a building, you’ll have to connect your cardboard together. But you can’t just hot glue along the sides. You have to use one of these three connecting methods:”
  • Cardboard connecting technique #1: L-brackets.

Cut a piece of cardstock a couple inches long and a bit smaller than the edges of cardboard you’re connecting.

Fold the cardstock in half, “hot dog” style.

Glue one fold to one piece of cardboard, and the other fold to the second piece of cardboard, making sure to match up the edges.

Here is the inside of an entire house connected with L-brackets:

  • Cardboard connecting technique #2: Slots

With either a box cutter/ X-Acto knife, or scissors, cut a slot halfway through your cardboard, no less than half an inch from the edge. Cut a slot halfway through the other piece of cardboard as well.

Insert the two pieces of cardboard into each other’s slots.

  • Cardboard connecting technique #3: Tab and slot

With an X-Acto knife/ box cutter, cut a slot no less than half an inch away from each edge of your first piece of cardboard. The slot should be the same thickness as the cardboard.

Cut away two corners of your second piece of cardboard to make a tab the same size as the slot.

Insert the tab into the slot.

4. Help the students with whichever connecting technique they choose. Completing the building may take more than one session.

5. Decorate the houses with pompoms, cotton balls, sequins, etc. (You may want to wait until after they’ve built in circuits to decorate).

Lesson Steps

(Inspired by the STEM Christmas Tree Building Challenge from this blog post)

  1. Ask how many students celebrate Christmas and put up a Christmas tree. For any that do not celebrate Christmas, assure them that the tree they build today can be any sort of pine tree they want.
  2. Introduce the challenge: “Today we will be building a Christmas tree that stands up by itself, using only 2 sheets of green cardstock and 4 craft sticks.”
  3. Do not create an example, or they might just copy you! Show the following picture as inspiration instead:

4. Be amazed at the designs the students come up with!

5. Let the students decorate the trees with pompoms, cotton balls, construction paper, sequins, etc. They may also want to add lights to them, though that may be harder than with the gingerbread houses.

Review of circuitry basics from haunted house week:

  • A circuit allows electricity to flow from a power source (e.g., a battery), through conductive lines (e.g., conductive tape, but usually it’s wires) to a “load”, which does something with the electricity, like light up or move. Then it flows back to the battery. The path must be a closed shape. The word “circuit” sounds like “circle,” but it doesn’t have to be a circle; it can be a square, rectangle, triangle, or any other closed shape!
  • A battery has a positive end and a negative end. Some lights, such as LEDs, have a positive and negative side too. In that case, the circuit has to go from the positive side of the battery to the positive side of the LED (the long leg), and from the negative side of the LED to the negative side of the battery.
  • A “switch” is any interruption in a circuit. When a switch is open, the circuit doesn’t work. When it is closed, the circuit works because the electricity can flow through the whole loop.

New concept: Parallel circuits—circuits with multiple LEDs:

  • A circuit can have multiple loads in two ways: series and parallel. A series circuit connects the loads in a single loop from the positive side of one to the negative side of the next. Putting two LEDs in series with a 3V battery will not work because each LED needs about 3V to light up, and a series circuit splits the voltage. Other loads that need less voltage might work in series.
  • A parallel circuit puts the multiple loads in multiple loops with the battery. The positive and negative sides of the loads do not touch each other in this type of circuit. Often a parallel circuit looks like two parallel lines. A 3V battery can light up multiple LEDs in parallel because parallel circuits split current, not voltage, so all LEDs can get the 3V they need to light up.

  • A note on LED colors: While a 3V battery can light up at least 10 LEDs in parallel, cool-colored LEDs mixed with warm-colored LEDs on the same parallel circuit will not light up. This is because cool colors need more energy to light up, and electricity is “lazy,” so it lights up only the LEDs that are easiest to light. Red and yellow work together, and blue, green, and white work together.

Step by step instructions

  1. Re-introduce circuits. Ask students if they remember how to make a circuit. Ask one to come up to the board and draw one. They should label the battery, light, and + and -. Correct if necessary.
  2. Then ask someone to draw what a circuit with 2 LEDs would look like. If they draw something that looks like a series circuit, explain that sometimes those work, but not in this case. Try to get someone to draw something like a parallel circuit. You may need to draw it yourself. In either case, explain parallel circuits quickly.
  3. Ask students to draw a circuit diagram where they want to put a parallel circuit on their cardboard building or Christmas tree. They should mark + and -, LED locations, and battery location. Check their diagrams.

4. Have the students place conductive tape on the negative line. Bend around any corners with the same piece of tape, since the adhesive is not very conductive.

5. Next students should place conductive tape for their positive side. They should make it at least one inch longer than needed. At the point where the tape will contact the battery, fold some tape back on itself to create a switch (i.e., when you press down on the switch, the positive line will touch the battery and the LEDs will turn on).

6. The long legs of your LEDs are positive. Bend your LEDs’ legs open and place the long legs on the positive side. Tape them down with non-conductive tape. Tape the negative legs on the negative side of your circuit.

7. Using non-conductive tape, place the battery in the space where it’s labeled to go. Don’t tape more than half of the battery to leave room for the switch to touch it. The positive side of the battery (the side with the words on it) should face up. Make sure the positive side of the battery will touch the positive line when the switch is pressed on top of it. The negative side should be touching the negative line of conductive tape. Use a binder clip to place the switch on top of the battery and complete the circuit.