Tag Archives: yeast

Thinking again

February 29, 2016 Ailie Rankin 1 Comment

So for Holly and indeed for anyone else, we revisited the toothpaste.

Revisiting learning and repeating activities and experiences helps us to process the information and deepen our learning.

This time around I focused more on letting the children take the lead and do as much as possible based on their last experience. As this was a repeat and more child led I didn’t bother with the logbooks.

Luckily we had a few re-visitors who could recall and share their experiences from Friday.

Again I tried to make this as hands on an experience as possible. Luckily the safety rules were firm in the children’s minds.

“Don’t touch the bottles! It’s dangerous!” – Gabriel

Ryan and Gabriel could both remember what we needed to do and what the reaction would be.

“We need the white stuff but it’s burny, and the smelly stuff to make it go up and over. ” – Ryan

So we measured out the yeast and took turns to mix…

We measured out the yeast powder in preparation for mixing it.

And we used those important hand muscles to add the washing up liquid.

And those pincer grips to squeeeeeeeeeeeeeze the yeast quickly into the hydrogen peroxide (the greater the force with which the yeast enters the mixture, the quicker the reaction).

And we weren’t disappointed in the reactions. In fact we did the experiment again and again and again using different colours.

The children grew in confidence with the foam and were able to notice it was hot.

“It’s like lava!” – Finlay F.

“But it looks like snow” – Adam

We noticed some of the mixtures went slower than others and so with a gloved hand I gave them a shake which really sped them up!

“Woah! Look at mine it’s going fast now!” – Nathan

“It got bigger!” – Elise

We repeated it so often we were left with lots of foam and it was lovely to play with (in fact we only stopped because we ran out of washing up liquid!)

“It’s all gooey looey!” – Finlay F.

And the colours all mixed again.

“This looks like a rainbow” – Ayvah

But Ryan used his knowledge of what we’d made to add to his observation..

“It’s like the elephant has already used all the toothpaste!” – Ryan D.

But the foam was perfect for mark making and writing secret spy messages! Great early writing practice.

The foam was perfect for writing and drawing.

The added opportunity to explore the process allowed Gabi to really add to her learning. She was able to explain what had happened to her friends…

“The yeast burned away the peroxide!” – Gabi

So a revisited experience but more learning all the same!

Sometimes it is worth thinking again.

chemistry

Elephant’s toothpaste in the main building

February 27, 2016 Ailie Rankin 1 Comment

After the excitement about the erruptions, explosions and gaseous experiences, I thought it only appropriate to revisit elephant’s toothpaste but this time with the main building children.

We used the same ingredients as last time.

Hydrogen peroxide, yeast, fairy liquid, washing up liquid, dye.

The same safety rules applied..

“No touching the bottles!” – Gabi

However, this time we added a little more of a hands on approach with the children using the droppers to add the yeast. This allows the children a level of responsibility (managing their own, all be it small, risk) which adds a level of engagement and greater involvement in the learning.

We used droppers, a beaker for the yeast mixture and a spoon for measuring and stirring.

There were a number of predictions in which the children applied knowledge gained from previous experiences….

"I predict that its going to right up to the roof and down!" — “I predict that its going to right up to the roof and down!”

“It’s going to besplode!!” – Heidi

"Its gonna overflow!" — “Its gonna overflow!”

Lara even used the correct vocabulary when making her prediction!!

“I predict it’ll go right up to the roof and back down” – Lara

But first we had to mix the yeast. This offered opportunity for the children to engage with real measure (of a spoonful) and counting the spoonfuls to add. They also had to take turns to mix the yeast as I deliberately only offered one spoon and one beaker.

Eilidh and Lily carefully measured out teaspoons of yeast powder into the beaker in preparation for mixing it to activate it.

We took turns to mix the yeast mixture. Ross and Isla revisited the experiment in the afternoon.

Lara, Olivia and Gabriel took turns to mix the yeast and water together to activate the yeast.

“Eeeuurgh it smells like a swamp or a dirty shoe!” – Ryan D.

Then we had to use those important hand muscles to squeeze the washing up liquid to the hydrogen peroxide that I had already poured into bottles.

We had to use our hand and finger muscles to squeeze the washing up liquid into our mixture.

We used washing up liquid to allow the gas to create bubbles and foam.

And so we were ready to add the yeast…

We used the droppers to add the yeast mixture safely.

Bramble focused and concentrated to squeeze all the yeast into the hydrogen peroxide quickly.

Caoimhe carefully added the yeast with the dropper.

And the results were quite good.

“Ross’s stayed the same but mine BESPLODED!!” – Heidi

"It was really really really foamy!" — “It was really really really foamy!”

We observed the experiment to monitor what happened.

The foam kept growing and growing. “It looks like a big ice cream!” – Patrick

Jude took a step back – unsure if it would explode!

Eilidh and and Lily explored the the texture of the foam with their hands as Ross and Eve mixed the yeast for the next batch.

We watched as the mixture grew and grew!

The mixture grew fast in some cases. “Look at mine – its overflowing!” – Isla

So why did it explode? We analysed the experiment..

“It was because we put too much yeast in” – Heidi

"It exploded because it made gas." — “It exploded because it made gas.”

Ross reported and shared what had happened. His remembering and discussing the bubble shows that he was thinking about it.

"First there was the bottle, then it all overflowed!" — “First there was the bottle, then it all overflowed!” – Ryan

The foam that it created was warm and harmless as the yeast had mixed with the hydrogen peroxide, burning all the peroxide away and releasing heat and oxygen which mixed with the washing up liquid to create the foam. Some of the mixtures needed a little help to get going so I gave them a little shake to mix them up and that worked a treat.

And of course the harmless foam was lovely for making patterns and marks (early writing) and exploring the colour mixing (yet more science)!

An said “We have a new colour now! Rainbow colour!”

James spent a long time investigating how the foam would drop from his hand on to his arm. He wanted to see how much he could pile up.

So what next?

Well Ryan gave us an excellent question to explore..

“What does disolve mean?” – Ryan

But the mixing of the coloured foam revealed another area to explore as the children created new colours.

“Look what colours I can make!” – James

And then I discovered Brandon’s interest in Angry Birds and thought about how we could explore forces further with catapults and towers…….hmmm

But Holly made it clear what we should do on Monday..

“Aww Ailie, I never saw the science today. Can we do it again on Monday?” – Holly

Well how could I resist? And I just so happen to have bought a stronger concentration of peroxide – I wonder what difference that will make?

Why not help me decide what direction to take after Monday? I will of course ask the children but please add your ideas too! Is there an experiment or science area you would like us to explore? Let me know!

In the meantime why not try to recreate some of these chemical reactions at home? You can buy hydrogen peroxide at Sally’s in the town and the yeast is available in the baking section of Tesco. Antibacterial washing up liquid doesn’t work so well so just go for the original kind, bubble bath works also.

Good luck and happy experimenting!

Campus, chemistry

Elephant’s Toothpaste

January 29, 2016 Ailie Rankin Leave a comment

While working on the potions it became clear that erupting and exploding reactions were the ones that the children sought the most. After a quick browse on Pinterest we came across Elephant’s Toothpaste. How could we resist?

We used hydrogen peroxide as part of this experiment which is obviously nasty on the skin so some time was spent discussing ways of ensuring we were safe. This is always part of our process but was especially focussed on for this experiment.

We were careful to keep our hands away from the bottles –

“It’s dangerous! Don’t touch! But we can watch.”

The hydrogen peroxide was mixed with a little washing up liquid and food colouring, grown ups needed to do that bit. The experiment used yeast as well which we could touch and so help with that.

We watched closely as Ailie carefully poured the chemicals together.

Then we poured the mixtures together….

We had a range of different predictions. Alfie thought the yeast would turn green. Millie predicted it would go bubbly. Jack thought it would turn into water. Everyone else just thought the colour would change. However no-one predicted quite what happened.

“It Exploded!!” – Alfie

It foamed up and over the top and kept growing.

The peroxide and yeast have an exothermic reaction (it releases heat) which burns all the peroxide away leaving hydrogen and oxygen which with the washing up liquid means it turns into harmless foam. The reaction continues until all the yeast or the peroxide is gone so the foam keeps growing.

Or as Ramsay put it…

There was a bottle and it went over the bottle and made a volcano!

Here are our volcanic eruptions:

Some seemed to go on for longer and make more foam.

We carefully touched the foam – it was warm!

When they slowed right down the, Ailie took the dangerous bottles away.

So then we were left with coloured foam. Hmmmm what could we do with that? Well we had to play and explore the texture and colours of course!

We were fascinated with the mixing colours.

The afternoon children were more tentative.

After a while it all turned pink and slimy.

We found we could draw patterns and marks in it.

It was great for early writing patterns.

Eventually the mixture got a little too runny. But it was fun to make a huge circle pattern by running around and around the tough spot. There was only one way to make it better….

The instructions for elephants toothpaste can be found on Pinterest. The hydrogen peroxide can be bought at Sally’s and the yeast can be bought at any supermarket in the baking section.

Please remember that anti bacterial washing up liquid is NOT to be used in the experiment. Cheap bubble bath can be substituted instead.

Why not have a go yourself? Don’t forget to share how you get on in our comments.

Happy experimenting!

Science blog from the children and staff of Kelly St. Children's Centre.