Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 243 · 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.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
2. 2.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) only an adult (c) any child (d) whoever is fastest
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) the juice scorches first (d) heat adds colour
4. 4.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
6. 6.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
7. 7.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
8. 8.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
9. 9.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
10. 10.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
11. 11.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
12. 12.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
13. 13.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) an adult with an iron (d) white paper
14. 14.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the ironing time (c) how dark the writing is
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) a battery cell (d) a small bowl
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
18. 18.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a cotton bud (d) a small bowl
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) a balloon (d) yeast
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
23. 23.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
24. 24.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
25. 25.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) letting the paper dry (c) writing the message (d) reading the message
26. 26.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) writing the message (c) ironing the paper (d) cutting the lemon
27. 27.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
29. 29.⚖️ 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 keep it the same (c) we change it
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud
31. 31.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
32. 32.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) dipping the cotton bud (c) writing the message (d) reading the message
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a magnet (c) turmeric powder (d) an adult with an iron
35. 35.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) putting the iron away (d) ironing the paper
36. 36.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
40. 40.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) reading the message (c) dipping the cotton bud (d) letting the paper dry

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