Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 205 · 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.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
2. 2.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
3. 3.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
4. 4.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) a cotton bud (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) the kind of juice (c) how dark the writing is
8. 8.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
9. 9.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) heat adds colour (c) the iron is brown (d) the juice scorches first
10. 10.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
11. 11.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
12. 12.🍋 Which of these steps is a job for an adult? (a) writing the message (b) reading the message (c) plugging in the iron (d) dipping the cotton bud
13. 13.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
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 ink is magnetic (d) the paper ate it
15. 15.True or false: letting the paper dry is a job for an adult. (a) True (b) False
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
17. 17.🍋 Which of these steps is a job for an adult? (a) ironing the paper (b) writing the message (c) letting the paper dry (d) reading the message
18. 18.⚖️ 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
19. 19.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
20. 20.⚖️ 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
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) an adult with an iron (d) white paper
22. 22.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it can burn skin (c) it is magnetic (d) it is sticky
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
24. 24.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
25. 25.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
26. 26.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) lemon juice (d) a mirror
27. 27.True or false: cutting the lemon is a job a child can do. (a) True (b) False
28. 28.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
29. 29.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
30. 30.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
32. 32.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
34. 34.True or false: reading the message is a job for an adult. (a) True (b) False
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) white paper (d) a small bowl
36. 36.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
37. 37.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) a magnet (d) a mirror
38. 38.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
39. 39.True or false: yeast is needed for the secret lemon message. (a) True (b) False
40. 40.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False

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