Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 789 · 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: a magnet is needed for the secret lemon message. (a) False (b) True
2. 2.⚖️ 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
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
4. 4.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
5. 5.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
6. 6.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
7. 7.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) an adult with an iron (d) a cotton bud
9. 9.True or false: letting the paper dry is a job for an adult. (a) True (b) False
10. 10.⚖️ 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 keep it the same (c) we change it
11. 11.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) the paper floats (c) writing turns green (d) it gets darker
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) reading the message
13. 13.⚖️ 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
14. 14.True or false: yeast is needed for the secret lemon message. (a) True (b) False
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) how dark the writing is (c) the iron setting
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same paper (c) the ironing time (d) the same cotton bud
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
18. 18.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
19. 19.⚖️ 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
20. 20.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
21. 21.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
22. 22.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the iron setting (c) the same cotton bud (d) how dark the writing is
24. 24.True or false: writing the message is a job for an adult. (a) True (b) False
25. 25.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we keep it the same (c) we measure it
28. 28.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a balloon (d) a small bowl
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
31. 31.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) cutting the lemon
32. 32.🍋 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) cutting the lemon
33. 33.True or false: plugging in the iron is a job a child can do. (a) False (b) True
34. 34.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) dipping the cotton bud (d) plugging in the iron
35. 35.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
36. 36.True or false: reading the message is a job for an adult. (a) False (b) True
37. 37.⚖️ 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 keep it the same (c) we measure it
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
39. 39.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the paper ate it (c) the ink is magnetic (d) dry juice is see-through
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) turmeric powder (d) lemon juice

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