Primary science - Grin and share it

What starts as a ridiculous statement can become an exciting lesson about teeth. Pour your class a drink and investigate, says Joanne Gilson

"What would happen if plants grew upside down? What if minibeasts were the size of cars?" These are a couple of the ridiculous questions that I give my pupils in the five minutes' brilliant ideas time we have at the start of each lesson.

Give children a ridiculous statement and ask them, based on their prior scientific knowledge, to work out what might happen and they will be motivated and enthusiastic.

I needed something exciting while teaching Year 3 pupils about teeth and this is what I came up with.

I explained that I had found a newspaper article that claimed some drinks were so bad for children's teeth that most 10-year-olds now needed dentures and all drinks except water should be banned from shops. The article then called for scientists to prove or disprove this theory.

We discussed brushing teeth, why this was important and that some foods can cause plaque to form on teeth, which causes decay. I then introduced them to a giant greeny-yellow face on a stick called Percy the Plaque Monster and talked about plaque.

The children brought in signed permission slips and their toothbrushes and toothpaste. We used dentists' disclosure tablets to show them that there was plaque on their teeth. Shock is the only word that can describe the looks on their faces. This promoted healthy discussion and hypotheses as to why some had more evidence of plaque than others.

After this, I arranged pupils into mixed-ability groups of about four to six and asked them how they would investigate the problem, pointing out that we would be using egg shells and not real teeth. In this Think-Pair- Share time, everyone gets a say, and if they don't have an idea, someone else will have one.

Here's how you can take it from here: make a list of their suggestions, no matter how bizarre. Next, plan the investigation together, asking the following questions:

- What are we going to investigate?

- What do we think will happen?

- How are we going to do it?

- What will we need?

- What will we measure?

- What are the results?

- What have we found out?

It takes a few lessons for pupils to get used to planning their own investigations, and you're never quite sure where they're going to lead.

However scary this is for the teachers, it motivates the children to see that science is exciting and if they have a question, there's a way to investigate it and come up with an answer.

The idea we eventually settled on was to investigate which of their favourite drinks would cause the most decay by measuring the effect on egg shells over a two-week period. We used digital blue cameras to record the shocking results.

Joanne Gilson is the science co-ordinator at Auckley Junior amp; Infant School in Auckley, Doncaster.

You can do it too

- Start with a "bright ideas" question.

- Allow the children to plan and investigate whatever they want to.

- Make sure the groups are mixed ability.

- Get hold of eggshells, disclosure tablets, drinks, containers, a digital camera and a fake newspaper article.

You know the lesson's going well when . there is laughter and excited voices saying: "Why don't we try this?" and "I wonder what would happen if we did this?"

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