Demonstration for surface area to volume ratio

So, surface area to volume ratio is a common concept in Science…

In digestion, they learnt that food are broken into small pieces so that it has larger surface area to volume ratio for enzymes to work on.

But, it’s hard to student to grasp the concept. They don’t get it how food in smaller pieces have larger exposed surface area to volume ratio.

So, here’s a simple demonstration.

First, make 2 jelly using red cabbage (reason being it’s a natural pH indicator) with identical moulds. Cut only 1 of the jelly into quarters. Then, add them into container of equal volume of lye water (alkaline solution).

Due to red cabbage being natural pH indicator, the jelly will change colour in alkaline solution (yellow in strong alkaline). As seen, the jellies cut in quarter turned yellow faster than the larger jelly because it has larger surface area to volume ratio.

2 jellies using identical mould. Only 1 jelly is cut into quarters.
The results of the demonstration.

Break the Code themed lessons

I started this year figuring out use of google forms for Break the Code themed lessons. I’ve been seeing such lessons by fellow teachers on IG/ FB and I guess it’s finally time for me to try in class. Better late than never, right?

One of the advantages of gamification of lessons is that it increases students’ motivation. This was the most evident during my lessons, because students took much faster time to complete the questions compared to paper-pen approach. I mean naturally most of us are competitive, right?

Having an interesting storyline helps too, for example by having role play for students to be on a challenge or mission. With this students are motivated to work towards the end goal.

The downside of this is time for planning such lessons. It is quite time consuming, but once you get the hang of it and everything comes together, trust me, it’ll be worth it. Especially after hearing from your students how they enjoyed it very much and when’s the next escape room/ break the code lesson 😉

Here are the 2 escape room/ break the code themed lessons I’ve done:

Save the animals

Let’s Discover Plants

Making Eco-enzyme

With the Chinese New Year celebration going on, it means plenty of mandarin oranges- the most common citrus fruit to make eco-enzyme.

So, what else do you need other than oranges?

Sugar, orange peels and water.

3 basic ingredients:

  • Sugar: food source for fermentation
  • Orange peels
  • Water

It’s that simple! Are you ready for a simple tutorial?

Add 1 part sugar
Add 3 parts orange peel, best to cut them into small pieces. The peels do not have to be washed/ scrubbed beforehand.
Top up with water and stir to dissolve the sugar.
Cover the bottle. For the first 10 days, remove cap to stir and release the carbon dioxide gas produced during fermentation, about 2 to 3 times daily. This is called the burping process. For this reason, it’s best to use plastic bottle, to allow room for expansion due to gas produced.

The eco-enzyme is ready about 3 months later or when all the peels sink.

So, what can you do with the eco-enzyme? Well, the common use is as a cleaning agent. Check out the tips below!

It’s that easy! So, will you be making the switch to green cleaning and making your own eco-enzyme? Let us know how yours turns out!

3D cardboard Christmas Tree

We have some cardboard boxes collected from neighbours for craft work, and since it’s the festive season, I decided to do up a Christmas tree, inspired from this website.

I didn’t do any measurement or use any template. Simply sketched directly on the board and cut it.

Cut-out of carboard Christmas tree

I cut another template and cut it vertically half. Then, we painted the pieces!

The last part, is to put them together and decorate it. In the spirit of upcycling, we used bottle caps and breadbag tags for decoration.

Such a easy-peasy DIY project to do with kids this holiday!

Electricity experiments tutorial

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.

Lesson on haze or air pollution

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.

Possible extension:
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

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.