Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 138 · 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? True or false: the kind of juice is kept the same. (a) True (b) False
2. 2.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a balloon (c) a cotton bud (d) white paper
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a balloon (d) yeast
6. 6.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
9. 9.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) white paper
11. 11.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) cutting the lemon (d) letting the paper dry
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
14. 14.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) the kind of juice (c) how dark the writing is
15. 15.⚖️ 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
16. 16.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
17. 17.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing
19. 19.True or false: putting the iron away is a job a child can do. (a) True (b) False
20. 20.⚖️ 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
21. 21.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) yeast (d) a small bowl
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we change it (c) we keep it the same
24. 24.⚖️ 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 change it (c) we measure it
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) lemon juice (d) white paper
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) lemon juice (c) a battery cell (d) an adult with an iron
27. 27.True or false: ironing the paper is a job a child can do. (a) False (b) True
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a battery cell (c) an adult with an iron (d) a balloon
29. 29.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a mirror (c) a magnet (d) a cotton bud
31. 31.🛟 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
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) white paper (d) yeast
33. 33.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) putting the iron away (d) writing the message
34. 34.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
36. 36.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) only an adult (d) whoever is fastest
37. 37.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) the paper floats (c) writing turns green (d) writing stays faint
38. 38.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it

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