Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 162 · 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.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
2. 2.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) lemon juice (c) a small bowl (d) a cotton bud
3. 3.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a balloon (d) a small bowl
4. 4.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
5. 5.True or false: cutting the lemon is a job for an adult. (a) False (b) True
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) turmeric powder (d) a cotton bud
7. 7.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) skip washing (d) lick your fingers
9. 9.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a cotton bud (c) turmeric powder (d) a balloon
10. 10.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
11. 11.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
13. 13.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a battery cell (c) an adult with an iron (d) a magnet
14. 14.True or false: cutting the lemon is a job a child can do. (a) True (b) False
15. 15.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a magnet (c) a battery cell (d) turmeric powder
17. 17.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a small bowl (c) white paper (d) a balloon
19. 19.⚖️ 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) how dark the writing is (c) the ironing time
20. 20.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) putting the iron away (d) letting the paper dry
21. 21.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
22. 22.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
23. 23.⚖️ 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
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) the iron is brown (c) heat adds colour (d) paper turns lemony
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the ironing time (b) the kind of juice (c) the same cotton bud (d) how dark the writing is
26. 26.🔍 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
27. 27.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
28. 28.True or false: reading the message is a job for an adult. (a) True (b) False
29. 29.🍋 Which of these steps is a job a child can do? (a) reading the message (b) ironing the paper (c) plugging in the iron (d) putting the iron away
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) False (b) True
31. 31.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) how dark the writing is (c) the kind of juice
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we measure it (c) we change it
34. 34.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
35. 35.⚖️ 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
36. 36.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
37. 37.⚖️ 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
38. 38.🔮 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
39. 39.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
40. 40.True or false: ironing the paper is a job a child can do. (a) False (b) True

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