Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 894 · 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.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) plugging in the iron (d) reading the message
2. 2.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
3. 3.⚖️ 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
4. 4.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) lemon juice (d) a cotton bud
6. 6.True or false: putting the iron away is a job a child can do. (a) True (b) False
7. 7.🛟 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
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) how dark the writing is (d) the kind of juice
9. 9.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) an adult with an iron (c) white paper (d) a mirror
10. 10.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
11. 11.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) paper turns lemony (d) the iron is brown
12. 12.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) reading the message (d) cutting the lemon
13. 13.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
14. 14.True or false: letting the paper dry is a job a child can do. (a) False (b) True
15. 15.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) dry juice is see-through (d) the ink is magnetic
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a battery cell
18. 18.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it can burn skin (c) it is cold (d) it is magnetic
20. 20.⚖️ 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 keep it the same (c) we change it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a balloon (c) a battery cell (d) a small bowl
23. 23.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same cotton bud (c) how dark the writing is
25. 25.🍋 Which of these steps is a job for an adult? (a) reading the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
26. 26.⚖️ 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
27. 27.⚖️ 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
28. 28.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
29. 29.True or false: writing the message is a job a child can do. (a) True (b) False
30. 30.True or false: yeast is not needed for the secret lemon message. (a) True (b) False
31. 31.⚖️ 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) False (b) True
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) the ironing time (c) the same cotton bud (d) how dark the writing is
33. 33.⚖️ 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) False (b) True
34. 34.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: ironing the paper is a job a child can do. (a) True (b) False
36. 36.🛟 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
37. 37.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a balloon (c) a mirror (d) a magnet
38. 38.True or false: reading the message is a job a child can do. (a) False (b) True
39. 39.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True

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