Lesson Plan 17 DIY Lava Lamp Brief description Students make a simple yet spectacular lava lamp using coloured water, vegetable oil and a soluble aspirin tablet. They write an instruction manual with diagrams and a scientific explanation of the observed effect. This activity is a big hit with kids and adults alike and will impress at dinner parties, barbecues and staff meetings too! Duration: Year level: Topics: Preparation: Extensions: 45-70 minutes Lower to upper primary Natural and Processed Materials, Energy and Change 5 to 15 minutes Write a report for the school newsletter / Make an instructional video for the DIY Lava Lamp / Investigate the invention and history of the Lava Lamp Overview Whole class Introduce and discuss lesson (10 15 min) Small Groups Make and observe DIY Lava Lamps (15 20 min) In small groups, students make and carefully observe a lava lamp. You may wish to photograph and video the procedure for the school newsletter or website this activity is a big hit with parents! Return vegetable oil to the bottle. Whole class Class discussion (5 15 min) Discuss the activity and any extension activities. Individual Write a DIY Lava Lamp Instruction Manual (15 20 min) Students write and illustrate an instruction manual providing a scientific explanation of the theory of operation. Lesson Plan 17 DIY Lava Lamp Page 1
Materials and equipment Total Quantity Description 2 litres Vegetable oil (200ml 300ml per group) 1 litre Water (50ml 100ml per group) 1 Set of four food colours (to share between groups) 6 Tall drinking glasses (1 per group) 18 Soluble aspirin tablets (3 per group) 1 roll Paper towel (for spills) 1 Turkey baster (for returning oil to bottle) 1 Bucket (to collect waste water and oil) Preparation Purchase vegetable oil, soluble aspirin and food colours from supermarket. Collect turkey baster, bucket and sufficient glasses for each group. Objectives Students prior knowledge No prior knowledge is required or assumed for this lesson plan. The objectives listed below are suggestions only and may not be appropriate for every year level. Science skills Students will: Predict whether oil and water will mix in a glass Predict and carefully observe how a drop of food colour behaves in vegetable oil and water Predict and observe how a soluble aspirin tablet behaves in vegetable oil and water Compare their predictions with observations Record their observations Lesson Plan 17 DIY Lava Lamp Page 2
Science concepts Vegetable oil and water do not mix substances which do not dissolve in each other are immiscible Vegetable oil floats on water because it is less dense Aspirin (acetyl salicylic acid) is a mild acid Soluble aspirin tablets also contain a mild base which reacts with the acidic aspirin when dissolved together in water to form bubbles of carbon dioxide gas The chemicals in soluble aspirin tablets do not dissolve in, and therefore do not react in, vegetable oil Positive attitudes Students will Work cooperatively with partners/group members Handle all equipment and water carefully and responsibly Dispose of waste responsibly (eg pour waste water and oil onto plants or garden beds instead of down the sink) Procedure Discuss lesson Whole Class (10 15 min) NOTE: a student worksheet is not provided for this activity because writing the instructions is a key component of the lesson. OPTIONAL: If you or any of your students own a lava lamp, bring it to the class and discuss how it works (the light bulb heats the waxy substance which causes it to expand and become buoyant so that it floats after sufficient cooling, the waxy substance shrinks and becomes less buoyant again so that it sinks the process repeats as long as the lamp is on) Write a basic outline of the procedure on the whiteboard and discuss each step NOTE: younger students may need supervision or assistance when adding the water and oil to the glass if so, groups can prepare materials and await your assistance for each step Lesson Plan 17 DIY Lava Lamp Page 3
Ask students to predict what will happen at each step ie: will the oil and water mix? how will a drop of food colour behave in oil? will the soluble aspirin tablet float or sink in the oil and how else might it behave? Assign group jobs and distribute materials required Make and observe DIY Lava Lamps Small Groups (15 20 min) Equipment Manager collects materials required for activity from science store Group members cooperate to make a Lava Lamp each group member should have a turn at adding one of the ingredients to glass: ¼ fill glass with water carefully add vegetable oil until glass is near full add two or three drops of food colouring and observe add soluble aspirin tablet and observe discuss ideas about how the lava lamp works NOTE: a whole class discussion about the theory of operation may assist groups to formulate and articulate their ideas at this point repeat, observe and revise ideas All group members cooperate to clean up Equipment manager returns equipment to science store NOTE: You may want to delay clean up so that early finishers can repeat the experiment Discussion Whole Class (5 10 min) Discuss the activity and observations Discuss how to approach writing and illustration of instruction guide students could design a one page illustrated instruction sheet or poster. Students could also take photographs for their instructions or make a video presentation (eg for the class BLOG on the school s website) Individual Whole Class (20 30 min) Students write and draw instructions in the format discussed above they can complete their instructions as a homework task if they run out of time Lesson Plan 17 DIY Lava Lamp Page 4
Teacher s notes How to make a DIY Lava Lamp 1. Quarter fill a tall glass with coloured water alternatively, use clear water at this stage and add a few drops of food colour after the oil is added. 2. 2. Add Hold oil the to glass the glass at an until angle it and is nearly gently full. top If up adding the glass with oil the drop of food colour now, it will sink through the oil without dissolving. It may take up to a minute for the drop to burst through the oil/water interface. 3. Add a soluble aspirin (or any other soluble tablet) and observe what happens. 4. The aspirin does not begin to dissolve until it breaks through and into the water. 5. The bubbles of carbon dioxide in the water make buoyant blobs which float in vegetable oil. When the blobs reach the surface, the bubbles pop so the blobs of water become less buoyant and sink again. 6. After removing the top layer, use a turkey baster to return the remaining oil to the bottle for re-use. Lesson Plan 17 DIY Lava Lamp Page 5