Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 536 · 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 small bowl for the secret lemon message? (a) not needed (b) needed
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we measure it (c) we change it
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
4. 4.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a mirror (c) an adult with an iron (d) lemon juice
6. 6.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
7. 7.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) the paper ate it (d) dry juice is see-through
9. 9.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
11. 11.⚖️ 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) True (b) False
12. 12.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) yeast (c) a battery cell (d) a small bowl
13. 13.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
14. 14.🧺 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 magnet (d) a cotton bud
15. 15.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a magnet
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a cotton bud (c) lemon juice (d) an adult with an iron
18. 18.⚖️ 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) how dark the writing is (c) the same paper (d) the kind of juice
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) True (b) False
21. 21.🛟 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
22. 22.True or false: reading the message is a job for an adult. (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.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a battery cell
25. 25.⚖️ 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 same paper
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
27. 27.⚖️ 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
28. 28.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
29. 29.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
30. 30.🧺 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) a balloon (d) lemon juice
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) reading the message (c) putting the iron away (d) ironing the paper
32. 32.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
33. 33.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
34. 34.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the same cotton bud
36. 36.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
37. 37.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
38. 38.⚖️ 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
39. 39.🔍 Which is the odd one out? (a) letting the paper dry (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
40. 40.True or false: putting the iron away is a job for an adult. (a) False (b) True

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