Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 329 · 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.True or false: putting the iron away is a job a child can do. (a) False (b) True
2. 2.True or false: reading the message is a job for an adult. (a) True (b) False
3. 3.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
4. 4.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a small bowl (c) an adult with an iron (d) white paper
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
7. 7.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) white paper (d) an adult with an iron
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) white paper (c) a cotton bud (d) a small bowl
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) the ink is magnetic (c) dry juice is see-through (d) it turned into air
11. 11.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) how dark the writing is (c) the same paper (d) the kind of juice
16. 16.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a cotton bud (c) an adult with an iron (d) lemon juice
18. 18.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
19. 19.True or false: writing the message is a job for an adult. (a) False (b) True
20. 20.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) dark brown words (c) almost nothing (d) a rainbow
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) a mirror (d) a small bowl
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) a cotton bud (d) an adult with an iron
24. 24.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
25. 25.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) putting the iron away (c) dipping the cotton bud (d) ironing the paper
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) a small bowl (c) white paper (d) a cotton bud
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.True or false: ironing the paper is a job for an adult. (a) False (b) True
29. 29.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
30. 30.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it can burn skin (d) it is magnetic
31. 31.True or false: letting the paper dry is a job a child can do. (a) False (b) True
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) a cotton bud (d) white paper
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
34. 34.🔍 Which is the odd one out? (a) letting the paper dry (b) ironing the paper (c) plugging in the iron (d) putting the iron away
35. 35.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
36. 36.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
37. 37.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
38. 38.True or false: ironing the paper is a job a child can do. (a) False (b) True
39. 39.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) reading the message (c) dipping the cotton bud (d) writing the message
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a mirror (c) white paper (d) a cotton bud

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