Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 867 · 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 turmeric powder for the secret lemon message? (a) needed (b) not needed
2. 2.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
3. 3.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) reading the message (d) dipping the cotton bud
4. 4.⚖️ 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
5. 5.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) blue words (c) almost nothing (d) dark brown words
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a small bowl (c) a cotton bud (d) a magnet
7. 7.True or false: plugging in the iron is a job for an adult. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) dipping the cotton bud (d) putting the iron away
9. 9.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
10. 10.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) green (c) brown (d) blue
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) how dark the writing is (c) the same cotton bud (d) the same paper
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a mirror (d) a cotton bud
14. 14.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
15. 15.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) writing the message (d) putting the iron away
17. 17.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
19. 19.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) white paper (c) a battery cell (d) an adult with an iron
20. 20.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) a magnet (d) lemon juice
21. 21.⚖️ 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
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a battery cell (d) a cotton bud
23. 23.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
24. 24.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
26. 26.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon
27. 27.⚖️ 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
28. 28.True or false: writing the message is a job for an adult. (a) True (b) False
29. 29.⚖️ 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
30. 30.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
31. 31.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
33. 33.True or false: white paper is needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the iron setting (c) the kind of juice
35. 35.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is sticky (c) it is cold (d) it is magnetic
36. 36.⚖️ 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
37. 37.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
38. 38.True or false: ironing the paper is a job a child can do. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a magnet (c) a battery cell (d) lemon juice
40. 40.True or false: ironing the paper is a job for an adult. (a) True (b) False

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