In our lesson I had made some red cabbage indicator the day before (hint - don't put it in a lemonade bottle no matter how well you think you washed it out!).
I started the session by asking the children what they knew about acids and alkalis. We then had a short discussion about uses and applications (e.g. stomach acid which aids digestion, high alkalinity in household cleaners) before I gave the kids some cards with various products on. I asked them to sort them according to whether they thought they were acidic, neutral or alkaline.
To test their theory we took it in turns to test some of the products with the red cabbage indicator. You'll need to give the children the sheet with the recording table on, and the sheet which shows the cabbage indicator scale at the top. As they test each item, they should fill in the sheet with the colour and their estimated pH. For ease and safety, I just had a volunteer to do each one under my supervision, but I only have a small group of five so everyone got a turn anyway.
The products we used which worked well were:
Bicarbonate of soda
Cream of tartar
Bleach (I did this one, and saved it for last - you'll see why when you do it yourself!)
I also made some litmus by soaking a couple of coffee filters in the cabbage indicator and cutting into strips. I showed the kids how this worked by dropping a bit of lemon juice onto it - it goes a lovely pink :-)
Finally, the other chart on the last page shows what other foodstuffs can be used as indicators, and their colour ranges. I've not tried them myself but it's all very interesting. I had so mch fun testing various bits and bobs at home, and the kids really loved this activity.