Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 111 · 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 kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
2. 2.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
3. 3.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) an adult with an iron (d) a mirror
4. 4.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) writing the message (d) cutting the lemon
5. 5.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) whoever is fastest (c) only an adult (d) any child
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) the same paper (c) how dark the writing is (d) the kind of juice
8. 8.🔍 Which is the odd one out? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) putting the iron away
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) white paper (d) turmeric powder
10. 10.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) dipping the cotton bud
11. 11.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
12. 12.True or false: cutting the lemon is a job for an adult. (a) True (b) False
13. 13.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) yeast
15. 15.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) cutting the lemon (c) plugging in the iron (d) ironing the paper
16. 16.True or false: reading the message is a job for an adult. (a) True (b) False
17. 17.⚖️ 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) False (b) True
18. 18.⚖️ 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) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) how dark the writing is (d) the same paper
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a magnet (d) a mirror
21. 21.True or false: ironing the paper is a job for an adult. (a) True (b) False
22. 22.🔍 Which is the odd one out? (a) writing the message (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
23. 23.True or false: a mirror is not needed for the secret lemon message. (a) True (b) False
24. 24.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) lick your fingers (d) rub your eyes
27. 27.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
28. 28.🍋 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
29. 29.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) writing the message (d) ironing the paper
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a cotton bud (c) white paper (d) lemon juice
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
32. 32.True or false: putting the iron away is a job a child can do. (a) False (b) True
33. 33.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
34. 34.⚖️ 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
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the iron is brown (c) paper turns lemony (d) the juice scorches first
36. 36.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) reading the message
37. 37.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) writing the message (c) dipping the cotton bud (d) reading the message
38. 38.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a magnet (c) turmeric powder (d) a small bowl
39. 39.🍋 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) putting the iron away
40. 40.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it

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