Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 364 · 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: lemon juice is not 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 iron setting is what we measure. (a) False (b) True
3. 3.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) reading the message (c) dipping the cotton bud (d) letting the paper dry
5. 5.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) lemon juice (d) a battery cell
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we change it (c) we keep it the same
8. 8.🔍 Which is the odd one out? (a) writing the message (b) reading the message (c) dipping the cotton bud (d) cutting the lemon
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) plugging in the iron (d) cutting the lemon
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) the paper ate it (c) the ink is magnetic (d) it turned into air
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
12. 12.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
13. 13.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
14. 14.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
15. 15.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
16. 16.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
17. 17.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
18. 18.🧺 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
19. 19.⚖️ 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
20. 20.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) turmeric powder (c) yeast (d) a small bowl
21. 21.True or false: yeast is needed for the secret lemon message. (a) False (b) True
22. 22.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
23. 23.🧺 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) turmeric powder
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 change it (b) we measure it (c) we keep it the same
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a cotton bud (c) a small bowl (d) turmeric powder
26. 26.True or false: writing the message is a job for an adult. (a) False (b) True
27. 27.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
28. 28.🛟 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
29. 29.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) white paper (d) lemon juice
33. 33.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
34. 34.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
35. 35.True or false: plugging in the iron is a job for an adult. (a) True (b) False
36. 36.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a mirror (c) white paper (d) lemon juice
37. 37.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
38. 38.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) white paper (d) a magnet
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the ironing time (d) the kind of juice
40. 40.True or false: cutting the lemon is a job for an adult. (a) False (b) True

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