Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 85 · 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.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) rub your eyes (d) lick your fingers
3. 3.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
4. 4.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if cooled (c) yes, if shaken (d) no, it stays brown
5. 5.🍋 Which of these steps is a job a child can do? (a) writing the message (b) cutting the lemon (c) putting the iron away (d) plugging in the iron
6. 6.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
7. 7.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) dark brown words (d) almost nothing
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) a balloon (d) a small bowl
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) white paper (c) a small bowl (d) a battery cell
10. 10.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) letting the paper dry (d) writing the message
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) a small bowl (d) turmeric powder
12. 12.True or false: plugging in the iron is a job for an adult. (a) True (b) False
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) the paper floats (d) writing stays faint
14. 14.True or false: ironing the paper is a job a child can do. (a) True (b) False
15. 15.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
16. 16.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
17. 17.⚖️ 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
18. 18.🍋 Secret message: who does this step — letting the paper dry? (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 same paper”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🔍 Which is the odd one out? (a) putting the iron away (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
21. 21.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) ironing the paper (d) dipping the cotton bud
22. 22.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
23. 23.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
24. 24.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) white (c) green (d) brown
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) yeast (d) a cotton bud
26. 26.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a magnet (d) a battery cell
27. 27.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) reading the message (d) cutting the lemon
28. 28.🔍 Which is the odd one out? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) cutting the lemon
29. 29.True or false: white paper is needed for the secret lemon message. (a) True (b) False
30. 30.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) cutting the lemon (d) plugging in the iron
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
32. 32.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) heat adds colour (c) the juice scorches first (d) paper turns lemony
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a mirror (d) a battery cell
34. 34.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the ink is magnetic (c) the paper ate it (d) it turned into air
35. 35.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) lemon juice (d) a cotton bud
39. 39.⚖️ 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
40. 40.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron

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