Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 904 · 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.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
2. 2.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
3. 3.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) brown (d) green
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
5. 5.⚖️ 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
6. 6.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) letting the paper dry (d) putting the iron away
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) ironing the paper (d) writing the message
9. 9.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) rub your eyes (c) skip washing (d) wash your hands
10. 10.True or false: cutting the lemon is a job for an adult. (a) True (b) False
11. 11.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it is cold (d) it can burn skin
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
14. 14.🍋 Why does the lemon writing turn brown with heat? (a) the juice scorches first (b) paper turns lemony (c) heat adds colour (d) the iron is brown
15. 15.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the kind of juice (d) the iron setting
17. 17.⚖️ 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
18. 18.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
19. 19.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) True (b) False
21. 21.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) an adult with an iron (c) a magnet (d) yeast
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a magnet (c) white paper (d) a small bowl
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) dark brown words (d) a rainbow
24. 24.⚖️ 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 kind of juice (c) the iron setting
25. 25.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a cotton bud (d) a mirror
26. 26.⚖️ 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 same cotton bud (c) the kind of juice
27. 27.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
28. 28.True or false: yeast is needed for the secret lemon message. (a) False (b) True
29. 29.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
30. 30.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a balloon (d) white paper
31. 31.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
32. 32.🧺 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) lemon juice (d) a mirror
33. 33.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
34. 34.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
35. 35.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
36. 36.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
37. 37.🔮 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
38. 38.🍋 Which of these steps is a job for an adult? (a) reading the message (b) letting the paper dry (c) dipping the cotton bud (d) putting the iron away
39. 39.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) turmeric powder (d) an adult with an iron

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