Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 582 · 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.⚖️ 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 same cotton bud (c) the same paper (d) how dark the writing is
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing stays faint (c) the paper floats (d) writing turns green
3. 3.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) a mirror (d) an adult with an iron
4. 4.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) lemon juice (d) turmeric powder
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a balloon (c) a small bowl (d) a magnet
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) ironing the paper (d) writing the message
7. 7.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
8. 8.🍋 Why can’t you see the lemon writing once it dries? (a) dry juice is see-through (b) it turned into air (c) the paper ate it (d) the ink is magnetic
9. 9.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) writing the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the iron setting (c) the same paper (d) the same cotton bud
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
12. 12.🔍 Which is the odd one out? (a) dipping the cotton bud (b) reading the message (c) plugging in the iron (d) writing the message
13. 13.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) a cotton bud (d) a balloon
14. 14.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
15. 15.⚖️ 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 change it (c) we keep it the same
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) dipping the cotton bud (d) putting the iron away
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
19. 19.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
20. 20.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) letting the paper dry (d) ironing the paper
21. 21.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
24. 24.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
25. 25.True or false: cutting the lemon is a job for an adult. (a) False (b) True
26. 26.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) the youngest child (d) only an adult
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) blue (d) brown
31. 31.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
32. 32.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
33. 33.🧺 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
34. 34.True or false: putting the iron away is a job for an adult. (a) True (b) False
35. 35.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) paper turns lemony (c) the iron is brown (d) the juice scorches first
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a magnet (b) a cotton bud (c) lemon juice (d) white paper
37. 37.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
38. 38.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
39. 39.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) plugging in the iron (d) letting the paper dry
40. 40.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) blue words (c) a rainbow (d) almost nothing

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