Experiments on the topic of experiments can be tricky because there are just a lot of variables that can affect the brightness of bulbs.
I’ve made 3 videos for this. Results are not shown in the earlier part of the video, so students will still have to carry out the experiment to record the results.
Effect of number of bulbs, arranged in series, on brightness of the bulbs.
Effect of number of batteries, arranged in series, on brightness of the bulbs.
Effect of number of bulbs, arranged in parallel, on brightness of the bulbs.
A simple demo to demonstrate the distribution of stomata on a leaf.
Demonstration set of haze/ air pollution
Creating haze in a beaker.
1. Measure and prepare aluminium foil to cover beaker.
2. Light up wooden splint and drop it into a beaker.
3. Cover with aluminium foil.
4. Place ice on it.
Use white paper towel to wipe the inner surface. Students will be able to observe very fine soot
Possible changes, use leaves and soil as a close set-up to forest. But didn’t work too well when I tried. Leaves must be really dry to burn/catch fire.
Egg membrane paper ball (my students said it looks like ping pong ball and they can toss it around.
1. Poke thru 2 holes using optical pin, one at the top and another at the bottom
2. Students chip off for a slighlty bigger hole (not too big!)
3. Remove egg content by draining it through the hoke or blowing thru it using a straw (straw need not be thru the hole, can place it just above.
4. Place egg in a beaker containing HCl. Use glass rod to ensure egg doesn’t float.
5. After 5min, discard off HCl. Place egg on petri dish. Gently tap the shell to crack it.
6. Pick up the membrane and rinse it.
7. Blow through it using straw so it inflate. Simply place the straw above the hole.
8. Roll it in talcum powder.
9. Allow it to dry.
Remove shell of raw quail egg by soaking it in Hydrochloric acid or vinegar for a day. Rinse it and place it in various set-up to demonstrate diffusion and osmosis.
From left to right:
Untreated, in distilled water, in red-coloured water, in honey.
One of my favourite lesson package to carry out for lesson on density is “Gold Ingot Scam”. It’s in the form of a case study in which students role-play as police officers. This is based on a real crime in Singapore in 2011.
I like this activity because there are videos from Crimewatch that can be used for pre and post lesson. In fact, in the part 2 of the video, it shows the detective carrying out the experiment.
I did this as a group work with my students.
Each group receive an electronic balance, a pendulum bob wrapped with Ferero Roche gold foil and a measuring cylinder.
The pendulum bob is kinda tricky though. The small one will not show much increase in water level, but the medium bob might get stuck in the cylinder. They kinda vary slightly in size, so you have to check beforehand. I was blessed with a lab tech who was willing to check that the medium bobs used did not get stuck in the cylinder. Luckily it was only 10 sets needed for him to check *phew*
I provided for the students a mock police report and a template for them to complete their report.
I did not provide instructions as I wanted the students to figure out on their own. Most generally got it that they have to measure mass and volume. But, while they’re were carrying out the experiment, I did spot some mistakes though.. such as
- Measuring volume, then mass (with water droplets still on sample!!)
- Not releasing the sample completely in the measuring cylinder. Some held on to the string, with the sample in the middle of the cylinder filled with water.
In the next lesson, I discussed these with them and elicit response from them on how those steps can affect the results.
For those keen for the lesson materials, you can get the materials here.
My favourite demo for the chapter on acid and alkali is…
red cabbage indicator
Add a pieces few leaves of red cabbage into a beaker of hot water. The leaves will decolourise and the solution will eventually turn purple. We will use this solution as the indicator. Add 2 drops into different samples and observe for colour change.
Colourful results from red cabbage indicator
Here’s my colourful result using these samples (from yellow, clockwise)
Lye water, bicarbonate of soda, sprite, detergent, lemon
Best used with samples that are colourless.
You can encourage students’ participation by allowing them to bring their own samples. Students generally are more excited to work on stuff that they contributed.
You can also extend this activity by giving them time to make their own indicator paper which they can bring home. Simply cut strips of filter paper, soak it in red cabbage juice and let it air dry. Students can then use them by dipping it into samples.