Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 241 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) brown (d) green
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we measure it (c) we keep it the same
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a battery cell (d) white paper
5. 5.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
8. 8.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
10. 10.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) plugging in the iron
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the iron setting (c) how dark the writing is (d) the same paper
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) a small bowl (d) a battery cell
13. 13.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) reading the message (c) plugging in the iron (d) ironing the paper
14. 14.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
15. 15.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) letting the paper dry (d) plugging in the iron
16. 16.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
17. 17.True or false: writing the message is a job a child can do. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
19. 19.True or false: putting the iron away is a job for an adult. (a) False (b) True
20. 20.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) lemon juice (d) turmeric powder
23. 23.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, if cooled (c) no, it stays brown (d) yes, in the dark
24. 24.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) a cotton bud (d) turmeric powder
25. 25.🔍 Which is the odd one out? (a) dipping the cotton bud (b) ironing the paper (c) letting the paper dry (d) writing the message
26. 26.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
27. 27.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
28. 28.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
29. 29.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
30. 30.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
33. 33.True or false: a magnet is needed for the secret lemon message. (a) False (b) True
34. 34.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
35. 35.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) ironing the paper
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a cotton bud (d) an adult with an iron
37. 37.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
39. 39.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True

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