Έτοιμοι για δράση;
Σχετικό υλικό
Σύνδεσμοι στο διαδίκτυο
Υλικό/Αρχεία προς μεταφόρτωση
Πόροι
Pasco system which includes Pasco capstone software + force platform, various soft/shock-absorbing materials (cotton wool, sand, bubble wrap, Styrofoam, leaves, grass, packaging materials, etc.), wooden ball, measuring tape, aluminium pan, Sad / happy balls
Προετοιμασία
Ask students to bring various shock-absorbing materials to class (if the playground has a covering of granular material, you can bring a sample of this too). Collect reserve materials for the activity (packaging materials, bubble wrap, sponges, Styrofoam, sand, etc.). Coordinate with a laboratory that has a Pasco or similar system (in secondary schools).
Στόχοι, μηνύματα, έννοιες
Συγεκεκριμένοι στόχοι
- Understand the risk and safety aspects of the playground.
- Measure the shock-absorbing property of different types of ground surface.
- Check the shock absorbing properties of the groundcover in the playground.
Συγκεκριμένα μηνύματα
- The design of the groundcover in the playground needs to take into account impact resistance and factors such as weather, slip, and water resistance.
- Shock absorption can be measured using an accelerometer.
- The better the shock absorption, the smaller the force applied on the surface.
Βασικοί όροι
- Shock absorption
- Force
Πρακτικές και Δεξιότητες
Πρακτικές STEM
- Ανάλυση και ερμηνεία δεδομένων
- Αιτιολόγηση και σχεδιασμός λύσεων
- Τεκμηριωμένη υπεράσπιση επιχειρηματολογίας
- Αξιοποίηση των μαθηματικών και της υπολογιστικής σκέψης
- Διατύπωση ερωτημάτων και προσδιορισμός προβλημάτων
- Προετοιμασία και διεξαγωγή έρευνας
Προσωπικές δεξιότητες
- Αντιμετώπιση της αβεβαιότητας
- Ομαδικό πνεύμα και συνεργασία
Δεξιότητες διαχείρισης
- Προσχεδιασμός
- Αξιοποίηση πόρων
Δράση
step 1
The challenge is to reduce the force of impact with the ground, during a fall at the playground. When an object falls, it is possible to calculate its speed, its acceleration, and its stored energy, but it is much more difficult to calculate the intensity of the impact.
step 2
Sad ball, happy ball demonstration:
- Show students 2 identical-looking balls which have a similar weight (let them feel).
- Drop the balls at the same time - one ball bounces and the other stays on the floor.
- Students should raise different hypotheses, i.e. the balls are made of different materials - the bouncing ball is made of synthetic rubber (neoprene), and the other ball is made of a special material (polynorbornene) that absorbs the energy and keeps it from bouncing at all.
- Extension: Why does the ‘happy’ ball bounce? What happened to the energy of the ‘sad’ ball? Conclusion: Impact with the floor depends on several factors such as the material of the ball, the material of the floor surface, and it is relatively complicated to calculate the intensity of the impact.
step 3
Next, students will complete a thought experiment: What does the intensity of the impact depend on? A child imagines placing a bowling ball on their foot. Students will consider how this differs from dropping the ball from waist height, explaining the physics behind the outcomes. Lastly, they will consider what would happen if a sponge or other soft material was placed over the foot and why.
step 4
Students will then conduct an experiment by throwing an egg against a stretched sheet. This introduces them to the concept of shock absorbency. Discuss how to measure the shock absorbency of a surface.
step 5
Research question: Which surface is best suited for the playground? Working in groups, students will brainstorm and come up with an idea for an experiment for testing the shock absorbency of the different materials. Identify the best way to test this event, taking into account it is very fast (in the scale of milliseconds – thousandths of a second!)
step 6
Falling objects experiment:
- This activity will involve the use of a Pasco force sensor to help measure the force of impact of a ball of a known mass dropped from a fixed height.
- Place a container holding various materials onto the platform and drop the ball into it, checking the force of the impact each time.
- Students present different possible materials for testing (both granular and solid materials).
- Experiment with the filling depth of granular materials, comparing how grain size and drop height affects the force of impact.
- Working in groups, each group will measure a particular variable, formulate a research question, and raise a hypothesis (see resources for detailed method).
- Discuss which type of material was the most shock absorbent, and the disadvantages of this material. Review which activities were undertaken during the test to include the force exerted by a falling ball onto the surface. How much force is considered dangerous? This is a complex question – there are many factors that affect it, and remember that a ball does not accurately simulate a child falling.
step 7
Explain how playground surfaces are tested to ensure it meets safety standards by simulating a child falling and checking the intensity of the impact. Explore other design factors such as durability, hygiene, ease of maintenance, non-slippage, water and weather resistance, etc. Does the surface selected meet these requirements? Is the surface suitable for wheelchairs, crutches or visual impairments?
step 8
Plenary question: What ground covering would be most suitable when building a playground?
step 9
Extension: Perform the ‘Egg Challenge’ at the playground, taking into account the things learned in this unit.