Take some lemon juice, add a little bit of water and you have invisible ink!. Wait for it to dry and then place close to a lightbulb and writing or picture will appear. Here is our artwork:

Then I put my paper close to a lightbulb to magically reveal what was there, but nothing happened 🙁 Then I realised the problem, unlike when I was younger, my new LED lightbulbs are not hot! So we used a candle. PLease note, when using a candle you should be careful not to burn the paper!!