Talking to people I got to know at various parent-and-toddler groups whilst on paternity leave, I came to realise there were barriers to other parents (and even teachers) doing this with their own children.

People sometimes assume it's easy for me because I'm a research scientist, but they couldn't possibly do the kind of activities I do with K     and E     because they have no science background. Maybe they imagine I have some wealth of science knowledge I can draw on. But I know as much biology, geology, zoology and most other -ologies as the next person! ^{55 5}My area of expertise is in quantum information theory. Which is not a whole lot of help when coming up with science ideas for 3-to-5 year olds!^{66 6}There's one quantum mechanics experiment I've done with K     and E     , and once or twice with older primary school children. I might write about it someday. I know that being a scientist gives me no big advantages over any other parent when it comes to doing science activities with children.

In fact, I think being a scientist gives me only two very minor advantages:

1. I'm perhaps less worried about trying out some experiment and it not working. And less worried about K     or E     asking me a science-related question I don't know the answer to. (They very often do!)
2. I'm more used to looking at the world scientifically. I tend to see opportunities at every turn to tell K     and E     about some interesting piece of science.

All it would take to negate these advantages are good quality, freely available science activity ideas aimed at pre-school children. Maybe not everyone is going to make up science experiments for 3-year-olds right away. But good resources go a long way to lowering the barriers to getting started.

In my view, good science activity resources for pre-school children need to achieve two things:

1. Provide well thought-through suggestions for simple science activities and experiments, that can be done with minimal preparation by time- and sleep-deprived parents of young children, wherever possible using only materials that can readily be found around the home.
2. Teach parents how to think like scientists. It's not enough to just explain the science behind the activities. Of course, that needs explaining too, simply and clearly, in a way that lets parents feel confident discussing the science involved with curious children armed with an endless supply of questions. But much more important is to explain to parents the scientific thinking going on in the activities.

Whilst I was on paternity leave, I scoured the internet for useful resources that would give me ready-made ideas for science activities for pre-school children.^{77 7}I was just as time- and sleep-deprived as the next parent! I was struck by how poor the available resources were. Most of what I found online or in books, billed as "science for kids", was either aimed at school-age children, or was very low-quality. Often just arts-and-crafts dressed up as science, with little if any real science content.^{88 8}Nothing wrong with arts-and-crafts! It's a really important part of childhood. But, unlike science activities, it's one that's very well catered for.

Over the last couple of years, as I came up with more science experiments and activities to do with K     and E     , and we tried them out multiple times, and refined and improved them, this became something we often did together at weekends or during holidays.^{99 9}Or during covid school closures! I collected a growing list of activities that were interesting and fun, worked well, and let them see for themselves how to think like a scientist. (As well as a growing list of tips for how not to do things!^{1010 10}Like: cress will die in a heatwave unless you water it at least twice a day until it's swimming in water! Or: it takes too long to put ice cubes into a plastic bottle; the air in the bottle cools down too much, before you manage to close the lid, for the air to compress significantly and crush the bottle. )

I wanted to give other parents of young children the resources and – more importantly – the confidence to start introducing their children to science from an early age. So I started writing these activities up.

I set myself the goals of:

• Coming up with science activities that require minimal preparation, and as far as possible use materials that are readily found around the home.
• Explaining the science behind the activities as simply but fully as I can, without over-simplifying or distorting the science for the sake of explanation.
• Explaining how simple experiments and activities – even if it's something a 3-year-old can do – teach more about how to think like a scientist than many university science degrees do!

These are tough goals, and I'm not going to manage to meet them every time. But they're good goals to aim for.

Writing these materials is a very slow process. It usually takes me multiple attempts to develop and refine an experiment or activity and try out different ways of doing it, before I'm happy enough with it to write it up. Then it takes me a long time to write it up properly. As parents everywhere know only too well, time seems to be in unimaginably short supply once you have children!

The list of science activities is growing much faster than I'm managing to write them. But I intend to slowly keep writing them up and posting them on this site as I find time.

The first few are here:

• Cress-Growing
• Floating and Sinking
• Buoyancy and Displacement